CHAPTER I. The Origin of Life

THE ORIGIN OF LIFE

§ 1. The Theory of Spontaneous Generation

Strictly speaking, the theory of Transformism is not concerned with the initial production of organic species, but rather with the subsequent differentiation and multiplication of such species by transmutation of the original forms. This technical sense, however, is embalmed only in the term transformism and not in its synonym evolution. The signification of the latter term is less definite. It may be used to denote any sort of development or origination of one thing from another. Hence the problem of the formation of organic species is frequently merged with the problem of the transformation of species under the common title of evolution.

This extension of the evolutionary concept, in its widest sense, to the problem of the origin of life on our globe is known as the hypothesis of abiogenesis or spontaneous generation. It regards inorganic matter as the source of organic life not merely in the sense of a passive cause, out of which the primordial forms of life were produced, but in the sense of an active cause inasmuch as it ascribes the origin of life to the exclusive agency of dynamic principles inherent in inorganic matter, namely, the physicochemical energies that are native to mineral matter. Life, in other words, is assumed to have arisen spontaneously, that is, by means of a synthesis and convergence of forces resident in inorganic matter, and not through the intervention of any exterior agency.

The protagonists of spontaneous generation, therefore, assert not merely a passive, but an active, evolution of living, from lifeless matter. As to the fact of the origin of the primal organisms from inorganic matter, there is no controversy whatever. All agree that, at some time or other, the primordial plants and animals emanated from inorganic matter. The sole point of dispute is whether they arose from inorganic matter by active evolution or simply by passive evolution. The passive evolution of mineral matter into plants and animals is an everyday occurrence. The grass assimilates the nitrates of the soil, and is, in turn, assimilated by the sheep, whose flesh becomes the food of man, and mineral substance is thus finally transformed into human substance. In the course of metabolic processes, the inorganic molecule may doff its mineral type and don, in succession, the specificities of plant, animal, and human protoplasm; and this transition from lower to higher degrees of perfection may be termed an evolution. It is an ascent of matter from the lowermost grade of an inert substance, through the intermediate grades of vegetative and animal life, up to the culminating and ultimate term of material perfection, in the partial constitution of a human nature and personality, in the concurrence as a coagent in vegetative and sensile functions, and in the indirect participation, as instrument, in the higher psychic functions of rational thought and volition.

At the present time, the inorganic world is clearly the exclusive source of all the matter found in living beings. All living beings construct their bodies out of inorganic substances in the process of nutrition, and render back to the inorganic world, by dissimilation and death, whatever they have taken from it. We must conclude, therefore, the matter of the primordial organisms was likewise derived from the inorganic world. But we are not warranted in concluding that this process of derivation was an active evolution. On the contrary, all evidence is against the supposition that brute matter is able to evolve of itself into living matter. It can, indeed, be transformed into plants, animals, and men through the action of an appropriate external agent (i.e. solely through the agency of the living organism), but it cannot acquire the perfections of living matter by means of its own inherent powers. It cannot vitalize, or sensitize, itself through the unaided activity of its own physicochemical energies. Only when it comes under the superior influence of preëxistent life can it ascend to higher degrees of entitive perfection. It does not become of itself life, sensibility, and intelligence. It must first be drawn into communion with what is already alive, before it can acquire life and sensibility, or share indirectly in the honors of intelligence (as the substrate of the cerebral imagery whence the human mind abstracts its conceptual thought). Apart from this unique influence, inorganic matter is impotent to raise itself in the scale of existence, but, if captured, molded, and transmuted by a living being, it may progress to the point of forming with the human soul one single nature, one single substance, one single person. The evolution of matter exemplified in organic metabolism is obviously passive, and such an evolution of the primal organisms out of non-living matter even the opponents of the hypothesis of spontaneous generation concede. But spontaneous generation implies an active evolution of the living from the lifeless, and this is the point around which the controversy wages. It would, of course, be utterly irrational to deny to the Supreme Lord and Author of Life the power of vivifying matter previously inanimate and inert, and hence the origin of organic life from inorganic matter by a formative (not creative) act of the Creator is the conclusion to which the denial of abiogenesis logically leads.

The hypothesis of spontaneous generation is far older than the theory of transformism. It goes back to the Greek predecessors of Aristotle, at least, and may be of far greater antiquity. It was based, as is well known, upon an erroneous interpretation of natural facts, which was universally accepted up to the close of the 17th century. As we can do no more than recount a few outstanding incidents of its long and interesting history here, the reader is referred to the VII chapter of Wasmann’s “Modern Biology” and the VIII chapter of Windle’s “Vitalism and Scholasticism” for the details which we are obliged to omit.

§ 2. The Law of Genetic Continuity—

From time immemorial the sudden appearance of maggots in putrescent meat had been a matter of common knowledge, and the ancients were misled into regarding the phenomenon as an instance of a de novo origin of life from dead matter. The error in question persisted until the year 1698, when it was decisively disproved by a simple experiment of the Italian physician Francesco Redi. He protected the meat from flies by means of gauze. Under these conditions, no maggots appeared in the meat, while the flies, unable to reach the meat, deposited their eggs on the gauze. Thus it became apparent that the maggots were larval flies, which emerged from fertilized eggs previously deposited in decaying meat by female flies. Antonio Vallisnieri, another Italian, showed that the fruit-fly had a similar life-history. As a result of these discoveries, Redi rejected the theory of spontaneous generation and formulated the first article of the Law of Genetic Vital Continuity: Omne vivum ex vivo.

Meanwhile, the first researches conducted by means of the newly invented compound microscope disclosed what appeared to be fresh evidence in favor of the discarded hypothesis. The unicellular organisms known as infusoria were found to appear suddenly in hay infusions, and their abrupt appearance was ascribed to spontaneous generation. Towards the end of the 18th century, however, a Catholic priest named Lazzaro Spallanzani refuted this new argument by sterilizing the infusions with heat and by sealing the containers as protection against contamination by floating spores or cysts. After the infusions had been boiled for a sufficient time and then sealed, no organisms could be found in them, no matter how long they were kept. We now know that protozoa and protophytes do not originate de novo in infusions. Their sudden appearance in cultures is due to the deposition of spores or cysts from the air, etc.

The possibility that the non-germination of life in sterilized infusions kept in sealed containers might be due to the absence of oxygen, removed by boiling and excluded by sealing, left open a single loophole, of which the 19th century defenders of abiogenesis proceeded to avail themselves. Pasteur, however, by employing sterilized cultures, which he aerated with filtered air exclusively, succeeded in depriving his opponents of this final refuge, and thereby completely demolished the last piece of evidence in favor of spontaneous generation. Prof. Wm. Sydney Thayer, in an address delivered at the Sorbonne, May 22, 1923, gives the following account of Pasteur’s experiments in this field: “Then, naturally (1860-1876) came the famous studies on spontaneous generation undertaken against the advice of his doubting masters, Biot and Dumas. On the basis of careful and well-conceived experiments he demonstrated the universal presence of bacteria in air, water, dust; he showed the variation in different regions of the bacterial content of the air; he demonstrated the permanent sterility of media protected from contamination, and he insisted on the inevitable derivation of every living organism from one of its kind. ‘No,’ he said, ‘there is no circumstance known today which justifies us in affirming that microscopic organisms have come into the world, without parents like themselves. Those who made this assertion have been the playthings of illusions or ill-made experiments invalidated by errors which they have not been able to appreciate or to avoid.’ In the course of these experiments he demonstrated the necessity of reliable methods of sterilization for instruments or culture media, of exposure for half an hour to moist heat at 120° or to dry air at 180°. And behold! our modern procedures of sterilization and the basis of antiseptic surgery.” (Science, Dec. 14, 1923, p. 477.) Pasteur brought to a successful completion the work of Redi and Spallanzani. Henceforth spontaneous generation was deprived of all countenance in the realm of biological fact.

Meanwhile, the cytologists and embryologists of the last century were adding article after article to the law of genetic cellular continuity, thus forging link by link the fatal chain of severance that inexorably debars abiogenesis from the domain of natural science. With the formulation of the great Cell Theory by Schleiden and Schwann (1838-1839), it became clear that the cell is the fundamental unit of organization in the world of living matter. It has proved to be, at once, the simplest organism capable of independent existence and the basic unit of structure and function in all the more complex forms of life. The protists (unicellular protozoans and protophytes) consist each of a single cell, and no simpler type of organism is known to science. The cell is the building brick out of which the higher organisms or metists (i.e. the multicellular and tissued metazoans and metaphytes) are constructed, and all multicellular organisms are, at one time or other in their career, reduced to the simplicity of a single cell (v.g. in the zygote and spore stages). The somatic or tissue cells, which are associated in the metists to form one organic whole, are of the same essential type as germ cells and unicellular organisms, although the parallelism is more close between the unicellular organism and the germ cell. The germ cell, like the protist, is equipped with all the potentialities of life, whereas tissue cells are specialized for one function rather than another. The protist is a generalized and physiologically-balanced cell, one which performs all the vital functions, and in which the suppression of one function leads to the destruction of all the rest; while the tissue cell is a specialized and physiologically-unbalanced cell limited to a single function, with the other vital functions in abeyance (though capable of manifesting themselves under certain circumstances). Normally, therefore, the tissue cell is functionally incomplete, a part and not a whole, whereas the protist is an independent individual, being, at once, the highest type of cell and the lowest type of organism.

According to the classic definition of Franz Leydig and Max Schultze, the cell is a mass of protoplasm containing a nucleus, both protoplasm and nucleus arising through division of the corresponding elements of a preëxistent cell. In this form the definition is quite general and applies to all cells, whether tissue cells, germ cells, or unicellular organisms. Moreover, it embodies two principles which still further determine the law of genetic cellular continuity, namely: Omnis cellula ex cellula, enunciated by Virchow in 1855, and Flemming’s principle: Omnis nucleus ex nucleo, proclaimed in 1882. In this way, Cytology supplemented Redi’s formula that every living being is from a preëxistent living being, by adding two more articles, namely, that every living cell is from a preëxistent cell, and every new cellular nucleus is derived by division from a preëxistent cellular nucleus. Now neither the nucleus nor the cell-body (the cytoplasm or extranuclear area of the cell) is capable of an independent existence. The cytoplasm of the severed nerve fibre, when it fails to reëstablish its connection with the neuron nucleus, degenerates. The enucleated amœba, though capable of such vital functions as depend upon destructive metabolism, can do nothing which involves constructive metabolism, and is, therefore, doomed to perish. The sperm cell, which is a nucleus that has sloughed off most of its cytoplasm, disintegrates, unless it regains a haven in the cytoplasm of the egg. Life, accordingly, cannot subsist in a unit more simply organized than the cell. No organism lives which is simpler than the cell, and the origin of all higher forms of life is reducible, as we shall see, to the origin of the cell. Consequently, new life can originate in no other way than by a process of cell-division. All generation or reproduction of new life is dependent upon the division of the cell-body and nucleus of a preëxistent living cell.

Haeckel, it is true, has attempted to question the status of the cell as the simplest of organisms, by alleging the existence of cytodes (non-nucleated cells) among the bacteria and the blue-green algæ. Further study, however, has shown that bacteria and blue-green algæ have a distributed nucleus, like that of certain ciliates, such as Dileptus gigas and Trachelocerca. In such forms the entire cell body is filled with scattered granules of chromatin called chromioles, and this diffuse type of nucleus seems to be the counterpart of the concentrated nuclei found in the generality of cells. At any rate, there is a temporary aggregation of the chromioles at critical stages in the life-cycle (such as cell-division), and these scattered chromatin granules undergo division, although their distribution to the daughter-cells is not as regular as that obtaining in mitosis. All this is strongly suggestive of their nuclear nature, and cells with distributed nuclei cannot, therefore, be classified as cytodes. In fact, the polynuclear condition is by no means uncommon. Paramœcium aurelia, for example, has a macronucleus and a micronucleus, and the Uroleptus mobilis has eight macronuclei and from two to four micronuclei. The difference between the polynuclear and diffuse condition seems to be relatively unimportant. In fact, the distributed nucleus differs from the morphological nucleus mainly in the absence of a confining membrane. From the functional standpoint, the two structures are identical. Hence the possession of a nucleus or its equivalent is, to all appearances, a universal characteristic of cells. Haeckel’s “cytodes” have proved to be purely imaginary entities. The verdict of modern cytologists is that Shultze’s definition of the cell must stand, and that the status of the cell as the simplest of organic units capable of independent existence is established beyond the possibility of prudent doubt.

With the progressive refinement of microscopic technique, it has become apparent that the law of genetic continuity applies not merely to the cell as a whole and to its major parts, the nucleus and the cell-body, but also to the minor components or organelles, which are seen to be individually self-perpetuating by means of growth and division. The typical cell nucleus, as is well known, is a spherical vesicle containing a semisolid, diphasic network of basichromatin (formerly “chromatin”) and oxychromatin (linin) suspended in more fluid medium or ground called nuclear sap. When the cell is about to divide, the basichromatin resolves itself into a definite number of short threads called chromosomes. Now, Boveri found that, in the normal process of cell-division known as mitosis, these nuclear threads or chromosomes are each split lengthwise and divided into two exactly equivalent halves, the resulting halves being distributed in equal number to the two daughter-cells produced by the division of the original cell. Hence, in the year 1903, Boveri added a fourth article to the law of genetic vital continuity, namely: Omne chromosoma ex chromosomate.

But the law in question applies to cytoplasmic as well as nuclear components. In physical appearance, the cell-body or cytoplasm resembles an emulsion with a clear semiliquid external phase called hyaloplasm and an internal phase consisting mainly of large spheres called macrosomes and minute particles called microsomes, all of which, together with numerous other formed bodies, are suspended in the clear hyaloplasm (hyaline ground-substance). Now certain of these cytoplasmic components have long been known to be self-perpetuating by means of growth and division, maintaining their continuity from cell to cell. The plastids of plant cells, for example, divide at the time of cell-division, although their distribution to the daughter-cells does not appear to be as definite and regular as that which obtains in the case of the chromosomes. Similarly, the centrioles or division-foci of animal cells are self-propagating by division, but here the distribution to the daughter-cells is exactly equivalent and not at random as in the case of plastids. In the light of recent research it looks as though two other types of cytoplasmic organelles must be added to the list of cellular components, which are individually self-perpetuating by growth and division, namely, the chondriosomes and the Golgi bodies—“both mitochondria and Golgi bodies are able to assimilate, grow, and divide in the cytoplasm.” (Gatenby.) Wilson is of opinion that the law of genetic continuity may have to be extended even to those minute granules and particles of the cytosome, which were formerly thought to arise de novo in the apparently structureless hyaloplasm. Speaking of the emulsified appearance of the starfish and sea urchin eggs, he tells us that their protoplasm shows “a structure somewhat like that of an emulsion, consisting of innumerable spheroidal bodies suspended in a clear continuous basis or hyaloplasm. These bodies are of two general orders of magnitude, namely: larger spheres or macrosomes rather closely crowded and fairly uniform in size, and much smaller microsomes irregularly scattered between the macrosomes, and among these are still smaller granules that graduate in size down to the limit of vision with any power (i.e. of microscope) we may employ.” (Science, March 9, 1923, p. 282.) Now, the limit of microscopic vision by the use of the highest-power oil-immersion objectives is one-half the length of the shortest waves of visible light, that is, about 200 submicrons (the submicron being one millionth of a millimeter). Particles whose diameter is less than this cannot reflect a wave of light, and are, therefore, invisible so far as the microscope is concerned. By the aid of the ultramicroscope, however, we are enabled to see the halos formed by particles not more than four submicrons in diameter, which, however, represents the limit of the ultramicroscope, and is the diameter hypothetically assigned to the protein multimolecule. Since, therefore, we find the particles in the protoplasm of the cell body graduating all the way down to the limit of this latter instrument, and since on the very limit of microscopic vision we find such minute particles as the centrioles “capable of self-perpetuation by growth and division, and of enlargement to form much larger bodies,” we cannot ignore the possibility that the ultramicroscopic particles may have the same powers and may be the sources or “formative foci” of the larger formed bodies, which were hitherto thought to arise de novo.

Certainly, pathology, as we shall see, tells us of ultramicroscopic disease-germs, which are capable of reproduction and maintenance of a specific type, and experimental genetics makes us aware of a linear alignment of submicroscopic genes in the nuclear chromosomes, each gene undergoing periodic division and perpetual transmission from generation to generation. The cytologist, therefore, to quote the words of Wilson, “cannot resist the evidence that the appearance of a simple homogeneous colloidal substance is deceptive; that it is in reality a complex, heterogeneous, or polyphasic system. He finds it difficult to escape the conclusion, therefore, that the visible and the invisible components of the protoplasmic system differ only in their size and degree of dispersion; that they belong to a single continuous series, and that the visible structure of protoplasm may give us a rough magnified picture of the invisible.” (Ibidem, p. 283.)

It would seem, therefore, that we must restore to honor, as the fifth article of the law of cellular continuity, the formula, which Richard Altmann enunciated on purely speculative grounds in 1892, but which the latest research is beginning to place on a solid factual basis, namely: Omne granulum ex granulo. “For my part,” says the great cytologist, Wilson, “I am disposed to accept the probability that many of these particles, as if they were submicroscopical plastids, may have a persistent identity, perpetuating themselves by growth and multiplication without loss of their specific individual type.” And he adds that the facts revealed by experimental embryology (e.g., the existence of differentiated zones of specific composition in the cytoplasm of certain eggs) “drive us to the conclusion that the submicroscopical components of the hyaloplasm are segregated and distributed according to an ordered system.” (Ibidem, p. 283.) The structure of the cell has often been likened to a heterogeneous solution, that is, to a complex polyphasic colloidal system, but this power of perpetual division and orderly assortment possessed by the cell as a whole and by its single components is the unique property of the living protoplasmic system, and is never found in any of the colloidal systems known to physical chemistry, be they organic or inorganic.

Cells, then, originate solely by division of preëxistent cells and even the minor components of the cellular system originate in like fashion, namely: by division of their respective counterparts in the preëxistent living cell. Here we have the sum and substance of the fivefold law of genetic continuity, whose promulgation has relegated the hypothesis of spontaneous generation to the realms of empty speculation. Waiving the possibility of an a priori argument, by which abiogenesis might be positively excluded, there remains this one consideration, which alone is scientifically significant, that, so far as observation goes and induction can carry us, the living cell has absolute need of a vital origin and can never originate by the exclusive agency of the physicochemical forces native to inorganic matter. If organic life exists in simpler terms than the cell, science knows nothing of it, and no observed process, simple or complicated, of inorganic nature, nor any artificial synthesis of the laboratory, however ingenious, has ever succeeded in duplicating the wonders of the simplest living cell.

§ 3. Chemical Theories of the Origin of Life

In fact, the very notion of a chemical synthesis of living matter is founded on a misconception. It would, indeed, be rash to set limits to the chemist’s power of synthesizing organic compounds, but living protoplasm is not a single chemical compound. Rather it is a complex system of compounds, enzymes and organelles, coördinated and integrated into an organized whole by a persistent principle of unity and finality. Organic life, to say nothing at all of its unique dynamics, is a morphological as well as a chemical problem; and, while it is conceivable that the chemist might synthesize all the compounds found in dead protoplasm, to reproduce a single detail of the ultramicroscopic structure of a living cell lies wholly beyond his power and province. “Long ago,” says Wilson (in the already quoted address on the “Physical Basis of Life”), “it became perfectly plain that what we call protoplasm is not chemically a single substance. It is a mixture of many substances, a mixture in high degree complex, the seat of varied and incessant transformations, yet one which somehow holds fast for countless generations to its own specific type. The evidence from every source demonstrates that the cell is a complex organism, a microcosm, a living system.” (Science, March 9, 1923, p. 278.)

With the chemist, analysis must precede synthesis, and it is only after a structural formula has been determined by means of quantitative analysis supplemented by analogy and comparison, that a given compound can be successfully synthesized. But living protoplasm and its structures elude such analysis. Intravitous staining is inadequate even as a means of qualitative analysis, and tests of a more drastic nature destroy the life and organization, which they seek to analyze. “With one span,” says Amé Pictet, Professor of Chemistry at the University of Geneva, “we will now bridge the entire distance separating the first products of plant assimilation from its final product, namely, living matter. And it should be understood at the outset that I employ this term ‘living matter’ only as an abbreviation, and to avoid long circumlocution. You should not, in reality, attribute life to matter itself; it has not, it cannot have both living molecules and dead molecules. Life requires an organization, which is that of cellular structure, but it remains, in contradistinction to it, outside the domain of strict chemistry. It is none the less true that the content of a living cell must differ in its chemical nature from the content of a dead cell. It is entirely from this point of view that the phenomenon of life pertains to my subject.... A living cell, both in its chemical composition and in its morphological structure, is an organism of extraordinary complexity. The protoplasm that it incloses is a mixture of very diverse substances. But if there be set aside on the one hand those substances which are in the process of assimilation and on the other those which are the by-products of nutrition, and which are in the process of elimination, there remain the protein or albuminous substances, and these must be considered, if not the essential factor of life, at least the theater of its manifestations.... Chemistry, however, is totally ignorant, or nearly so, of the constitution of living albumen, for chemical methods of investigation at the very outset kill the living cell. The slightest rise in temperature, contact with the solvent, the very powerful effect of even the mildest reactions cause the transformation that needs to be prevented, and the chemist has nothing left but dead albumen.” (Smithson. Inst. Rpt. for 1916, pp. 208, 209.)

Chemical analysis associated with physical analysis by means of the polariscope, spectroscope, x-rays, ultramicroscope, etc. is extremely useful in determining the structure of inorganic units like the atom and the molecule. Both, too, throw valuable light on the problem of the structure of non-living multimolecules such as the crystal units of crystalloids and the ultramicrons of colloids, but they furnish no clue to the submicroscopical morphology of the living cell. Such methods do not enable us to examine anything more than the “physical substrate” of life, and that, only after it has been radically altered; for it is not the same after life has flown. At all events, the integrating principle, the formative determinant, which binds the components of living protoplasm into a unitary system, which makes of them a single totality instead of a mere sum or fortuitous aggregate of disparate and uncoördinated factors, and which gives to them a determinate and persistent specificity that can hold its own amid a perpetual fluxion of matter and continual flow of energy, this is forever inaccessible to the chemist, and constitutes a phenomenon of which the inorganic world affords no parallel.

With these facts in mind, we can hardly fail to be amused whenever certain simple chemical reactions obtained in vitro are hailed as “clue to the origin of life.” When it was found, for instance, that, under certain conditions, an aldehyde (probably formaldehyde) is formed in a colloidal solution of chlorophyll in water, if exposed to sunlight, the discovery gave rise to Bach’s formaldehyde-hypothesis; for Alexis Bach saw in this reaction “a first step in the origin of life.” As formaldehyde readily undergoes aldol condensation into a syrupy fluid called formose, when a dilute aqueous solution of formaldehyde is saturated with calcium hydroxide and allowed to stand for several days, there was no difficulty in conceiving the transition from formaldehyde to the carbohydrates; for formose is a mixture containing several hexose sugars, and Fischer has succeeded in isolating therefrom acrose, a simple sugar having the same formula as glucose, namely: C₆H₁₂O₆. Glyceraldehyde undergoes a similar condensation. In view of these facts, carbohydrate-production in green plants was interpreted as a photosynthesis of these substances from water and carbon dioxide, with chlorophyll acting a sensitizer to absorb the radiant energy necessary for the reaction. The first step in the process was thought to be a reduction of carbonic acid to formic acid and then to formaldehyde, the latter being at once condensed into glucose, which in turn was supposed to be dehydrated and polymerized into starch. From the carbohydrates thus formed and the nitrates of the soil the plant could then synthesize proteins, while oxidation of the carbohydrates into fatty acids would lead to the formation of fats. Hence Bach regarded the formation of formaldehyde in the presence of water, carbon dioxide, chlorophyll, and sunlight as the “first step in the production of life.” Bateson, however, does not find the suggestion a very helpful one, and evaluates it at its true worth in the following contemptuous aside: “We should be greatly helped,” he says, “by some indication as to whether the origin of life has been single or multiple.” Modern opinion is, perhaps, inclined to the multiple theory, but we have no real evidence. Indeed, the problem still stands outside the range of scientific investigation, and when we hear the spontaneous formation of formaldehyde mentioned as a possible first step in the origin of life, we think of Harry Lauder in the character of a Glasgow schoolboy pulling out his treasures from his pocket—“That’s a wassher—for makkin’ motor cars.” (“Presidential Address,” cf. Smithson. Inst. Rpt. for 1915, p. 375.)

Bach, moreover, takes it for granted that the formation of formaldehyde is really the first step in the synthesis performed by the green plant, and he claims that formaldehyde is formed when carbon dioxide is passed through a solution of a salt of uranium in the presence of sunlight. Fenton makes a similar claim in the case of magnesium, asserting that traces of formaldehyde are discernible when metallic magnesium is immersed in water saturated with carbon dioxide. But at present it begins to look as though the spontaneous formation and condensation of formaldehyde had nothing to do with the process that actually occurs in green plants. Certain chemists, while admitting that an aldehyde is formed when chlorophyll, water, and air are brought together in the presence of sunlight, deny that the aldehyde in question is formaldehyde, and they also draw attention to the fact that this aldehyde may be formed in an atmosphere entirely destitute of carbon dioxide. In fact, the researches conducted by Willstätter and Stoll, and later (in 1916) by Jörgensen and Kidd tend to discredit the common notion that carbohydrate-production in plants is the result of a direct union of water and carbon dioxide. Botany textbooks still continue to parrot the traditional view. We cannot any longer, however, be sure but that the term photosynthesis may be a misnomer.

Carbohydrate-formation in plants seems to be more analogous to carbohydrate-formation in animals than was formerly thought to be the case. In animals, as is well known, glycogen or animal starch is formed not by direct synthesis, but by deämination and reduction of proteins. In a similar way, it is thought that the production of carbohydrates in plants may be due to a breaking down of the phytyl ester in chlorophyll, the chromogen group functioning (under the action of light) alternately as a dissociating enzyme in the formation of sugars and a synthesizing enzyme in the reconstruction of chlorophyll. Phytol is an unsaturated alcohol obtained when chlorophyll is saponified by means of caustic alkalis. Its formula is C₂₀H₃₉OH, and chlorophyll consists of a chromogen group containing magnesium (MgN₄C₃₂H₃₀O) united to a diester of phytyl and methyl alcohols.

Experimental results are at variance with the theory that chlorophyll acts as a sensitizer in bringing about a reduction of carbonic acid, after the analogy of eosin, which in the presence of light accelerates the decomposition of silver salts on photographic plates. Willstätter found that, when a colloidal solution of the pure extract of chlorophyll in water is exposed to sunlight and an atmosphere consisting of carbon dioxide exclusively, no formaldehyde is formed, but the chlorophyll is changed into yellow phæophytin owing to the removal of the magnesium from the chromogen group by the action of the carbonic acid. Jörgensen, on the other hand, discovered that in an atmosphere of pure oxygen, formaldehyde is formed, apparently by the splitting off and reduction of the phytyl ester of chlorophyll. Soon, however, the formaldehyde is oxidized to formic acid, which replaces the chlorophyllic magnesium with hydrogen, thus causing the green chlorophyll to degenerate into yellow phæophytin and finally to lose its color altogether. The dissociation of the chromogen group may be due to the fact that the reaction takes place in vitro, and may not occur in the living plant. At all events, it would seem that plants, like animals, manufacture carbohydrates by a destructive rather than a constructive process, and that water and carbon dioxide serve rather as materials for the regeneration of chlorophyll than as materials out of which sugars are directly synthesized.

A new theory has been proposed by Dr. Oskar Baudisch, who seems to have sensed the irrelevance of the formaldehyde hypothesis, and to have sought another solution in connection with the chromogen group of chlorophyll. He finds a more promising starting-point in formaldoxime, which, he claims, readily unites with such metals as magnesium and iron and with formaldehyde, in the presence of light containing ultra-violet rays, to form organic compounds analogous to the chromogen complexes in chlorophyll and hæmoglobin. Oximes are compounds formed by the condensation of one molecule of an aldehyde with one molecule of hydroxylamine (NH₂OH) and the elimination of a molecule of water. Hence Dr. Baudisch imagines that, given formaldoxime (H₂C:N·OH), magnesium, and ultra-violet rays, we might expect a spontaneous formation of chlorophyll leading eventually to the production of organic life. “It is his theory that life may have been caused through the direct action of sunlight upon water, air, and carbon dioxide in the ancient geologic past when, he believes, sunlight was more intense and contained more ultra-violet light and the air contained more water vapor and carbon dioxide than at the present time.” (Science, April 6, 1923, Supplement XII.)

This is the old Spencerian evasion, the fatuous appeal to “conditions unlike those we know,” the unverified and unverifiable assumption that an unknown past must have been more favorable to spontaneous generation than the known present. In archæozoic times, the temperature was higher, the partial pressure of atmospheric carbon dioxide greater, the percentage of ultra-violet rays in sunlight larger. Such contentions are interesting, if true, but, for all that, they may, “like the flowers that bloom in the spring,” have nothing to do with the case. Nature does not, and the laboratory cannot, reproduce the conditions which are said to have brought about the spontaneous generation of formaldoxime and its progressive transmutation into phycocyanin, chlorophyll and the blue-green algæ. What value, then, have these conjectures? If it be the function of natural science to discount actualities in favor of possibilities, to draw arguments from ignorance, and to accept the absence of disproof as a substitute for demonstration, then the expedient of invoking the unknown in support of a speculation is scientifically legitimate. But, if the methods of science are observation and induction, if it proceeds according to the principle of the uniformity of nature, and does not utterly belie its claim of resting upon factual realities rather than the figments of fancy, then all this hypothecation, which is so flagrantly at variance with the actual data of experience and the unmistakable trend of inductive reasoning, is not science at all, but sheer credulity and superstition.

When we ask by what right men of science presume to lift the veil of mystery from a remote past, which no one has observed, we are told that the justification of this procedure is the principle of the uniformity of nature or the invariability of natural laws. Nature’s laws are the same yesterday, today, and forever. Hence the scientist, who wishes to penetrate into the unknown past, has only to “prolong the methods of nature from the present into the past.” (Tyndall.) If we reject the soundness of this principle, we automatically cut ourselves off from all certainty regarding that part of the world’s history which antecedes human observation. Either nature’s laws change, or they do not. If they never change, then Spontaneous Generation is quite as much excluded from the past as it is from the present. If, however, as Hamann and Fechner explicitly maintain, nature’s laws do change, then, obviously, no knowledge whatever is possible respecting the past, since it is solely upon the assumption of the immutable constancy of such laws that we can venture to reconstruct prehistory.

The puerile notion that the synthesis of organic substances in the laboratory furnishes a clue to the origin of organic life on earth is due to a confusion of organic, with living and organized, substances. It is only in the production of organic substances that the chemist can vie with the plant or animal. These are lifeless and unorganized carbon compounds, which are termed organic because they are elaborated by living organisms as a metaplastic by-product of their metabolism. Such substances, however, are not to be confounded with animate matter, e.g. a living cell and its organelles, or even with organized matter, e.g. dead protoplasm. These the chemist cannot duplicate; for vitality and organization, as we have seen, are things that elude both his analysis and his synthesis. Even with respect to the production of organic substances, the parallelism between the living cell and the chemical laboratory is far from being a perfect one. Speaking of the metaplastic or organic products of cells, Benjamin Moore says: “Most of these are so complex that they have not yet been synthesized by the organic chemist; nay, even of those that have been synthesized, it may be remarked that all proof is wanting that the syntheses have been carried out in identically the same fashion and by the employment of the same forms of energy in the case of the cell as in the chemist’s laboratory. The conditions in the cell are widely different, and at the temperature of the cell and with such chemical materials as are at hand in the cell no such organic syntheses have been artificially carried out by the forms of energy extraneous to living tissue.” (“Recent Advances in Physiology and Bio-Chemistry,” p. 10.) Be that as it may, however, the prospect of a laboratory synthesis of an organic substance like chlorophyll affords no ground whatever for expecting a chemical synthesis of living matter. The chlorophyllic tail is inadequate to the task of wagging the dog of organic life. In this connection, Yves Delage’s sarcastic comment on Schaaffhausen’s theory is worthy of recall. The latter had suggested (in 1892) that life was initiated by a chemical reaction, in which water, air, and mineral salts united under the influence of light and heat to produce a colorless Protococcus, which subsequently acquired chlorophyll and became a Protococcus viridis. “If the affair is so simple,” writes Delage, “why does not the author produce a few specimens of this protococcus in his laboratory? We will gladly supply him with the necessary chlorophyll.” (“La structure du protoplasma et les théories sur l’hérédité,” p. 402.)

Another consideration, which never appears to trouble the visionaries who propound theories of this sort, is the fact that the inert elements and blind forces of inorganic nature are, if left to themselves, utterly impotent to duplicate even so much as the feats of the chemical laboratory, to say nothing at all of the more wonderful achievements possible only to living organisms. In the laboratory, the physicochemical forces of the mineral world are coördinated, regulated, and directed by the guiding intelligence of the chemist. In that heterogeneous conglomerate, which we call brute matter, no such guiding principle exists, and the only possible automatic results are those which the fortuitous concurrence of blind factors avails to produce. Chance of this kind may vie with art in the production of relatively simple combinations or systems, but where the conditions are as complex as those, which the synthesis of chlorophyll presupposes, chance is impotent and regulation absolutely imperative. How much more is this true, when there is question of the production of an effect so complicatedly telic as the living organism! “I venture to think,” says Sir William Tilden, in a letter to the London Times (Sept. 10, 1912), “that no chemist will be prepared to suggest a process by which, from the interaction of such materials (viz., inorganic substances), anything approaching a substance of the nature of a proteid could be formed or, if by a complex series of changes a compound of this kind were conceivably produced, that it would present the characters of living protoplasm.” In the concluding sentence of his letter, the great chemist seems to deprecate even the discussion of a chemical synthesis of living matter, whether spontaneous or artificial. “Far be it from any man of science,” he says, “to affirm that any given set of phenomena is not a fit subject of inquiry and that there is any limit to what may be revealed in answer to systematic and well-directed investigation. In the present instance, however, it appears to me that this is not a field for the chemist nor one in which chemistry is likely to afford any assistance whatever.” In any case, the idea that a chaos of unassorted elements and undirected forces could succeed where the skill of the chemist fails is preposterous. No known or conceivable process, or group of processes, at work in inorganic nature, is equal to the task. Chance is an explanation only for minds insensible to the beauty and order of organic life.

Darwin inoculated biological science with this Epicurean metaphysics, when, in his “Origin of Species,” he ascribed discriminating and selective powers of great delicacy and precision to the blind factors of a heterogeneous and variable environment. He compared natural selection to artificial selection, and in so doing, he was led astray by a false implication of his own analogy—“I have called this principle,” he says, “by which each slight variation, if useful, is preserved, by the term natural selection, in order to mark its relation to man’s power of selection.” (“Origin of Species,” 6th ed., c. III, p. 58.) Having likened the unintelligent and fortuitous selection and elimination exercised by the environment to the intelligent and purposive selection and elimination practiced by animal breeders and horticulturists, he pressed the analogy to the unwarranted extent of attributing to a blind, lifeless, and impersonal aggregate of minerals, liquids, and gases superhuman powers of discretion. To preserve even the semblance of parity, he ought first to have expurgated the process of artificial selection by getting rid of the element of human intelligence, which lurks therein, and vitiates its parallelism with the unconscious and purposeless havoc wrought at random by the blind and uncoördinated agencies of the environment. If inorganic nature were a vast and multifarious mold, a preformed sieve with holes of different sizes, a separator for sorting coins of various denominations, Darwin’s idea would be, in some degree, defensible, but this would only transfer the problem of cosmic order and intelligence from the organism to the environment. As a matter of fact, the mechanism of the environment is far too simple in its structure and too general in its influence to account for the complexities and specificities of organisms, that is, for the morphology and specific differences of plants and animals. Hence the selective work of the environment is negligible in the positive sense, and consists, for the most part, in a tendency to eliminate the abnormal and the subnormal. On the other hand, the environment as well as the organism is fundamentally teleological, and the environmental mechanism, though simple and general, is nevertheless expressly preadapted for the maintenance of organic life. Henderson, the bio-chemist of Harvard, has shown conclusively, in his “Fitness of the Environment” (1913), that the environment itself has been expressly selected with this finality in view, and that the inorganic world, while not the active cause, is, nevertheless, the preördained complement of organic life.

Simple constructions may, indeed, be due to pure accident as well as deliberate art, inasmuch as they presuppose but few and easy conditions. Complex constructions, on the contrary, provided they be systematic and not chaotic, are not producible by accident, but only by art, because they require numerous and complicated conditions. Operating individually, the unconscious factors of inorganic nature can produce simple and homogeneous constructions such as crystals. Operating in uncoördinated concurrence with one another, these blind and unrelated agencies produce complex chaotic formations such as mountains and islands, mere heterogeneous conglomerates, destitute of any determinate size, shape, or symmetry, constructions in which every single item and detail is the result of factors each of which is independent of the other. In short, the efficacy of the unconscious and uncoordinated physicochemical factors of inorganic nature is limited to fortuitous results, which serve no purpose, embody no intelligible law, convey no meaning nor idea, and afford no æsthetic satisfaction, being mere aggregates or sums rather than natural units and real totalities. But it does not extend to the production of complex systematic formations such as living organisms or human artefacts. Left to itself, therefore, inorganic nature might conceivably duplicate the simplest artefacts such as the chipped flints of the savage, and it might also construct a complex heterogeneous chaos of driftwood, mud, and sand like the Great Raft of the Red River, but it would be utterly impotent to construct a complicated telic system comparable to an animal, a clock, or even an organic compound, like chlorophyll.

In this connection, it is curious to note how extremely myopic the scientific materialist can be, when there is question of recognizing a manifestation of Divine intelligence in the stupendous teleology of the living organism, and how incredibly lynx-eyed he becomes, when there is question of detecting evidences of human intelligence in the eoliths alleged to have been the implements of a “Tertiary Man.” In the latter case, he is never at a loss to determine the precise degree of chipping, at which an eolith ceases to be interpretable as the fortuitous product of unconscious processes, and points infallibly to the intelligent authorship of man, but he grows strangely obtuse to the psychic implications of teleology, when it comes to explaining the symmetry of a starfish or the beauty of a Bird of Paradise.

In conclusion, it is clear that the hypothesis of a spontaneous origin of organic life from inorganic matter has in its favor neither factual evidence nor aprioristic probability, but is, on the contrary, ruled out of court by the whole force of the scientific principle of induction. To recapitulate, there are no subcellular organisms, and all cellular organisms (which is the same as saying, all organisms), be they unicellular or multicellular, originate exclusively by reproduction, that is, by generation from living parents of the same organic type or species. This is the law of genetic vital continuity, which, by the way, Aristotle had formulated long before Harvey, when he said: “It appears that all living beings come from a germ, and the germ from parents.” (“De Generatione Animalium,” lib. I, cap. 17.) All reproduction, however, is reducible to a process of cell-division. That such is the case with unicellular organisms is evident from the very definition of a cell. That it is also true of multicellular organisms can be shown by a review of the various forms of reproduction occurring among plants and animals.

§ 4. =Reproduction and Rejuvenation=

Reproduction, the sole means by which the torch of life is relayed from generation to generation, the exclusive process by which living individuals arise and races are perpetuated, consists in the separation of a germ from the parent organism as a physical basis for the development of a new organism. The germ thus separated may be many-celled or one-celled, as we shall see presently, but the separated cells, be they one or many, have their common and exclusive source in the process of mitotic cell-division. In a few cases, this divisional power or energy of the cell seems to be perennial by virtue of an inherent inexhaustibility. In most cases, however, it is perennial by virtue of a restorative process involving nuclear reorganization. In the former cases, which are exceptional, the cellular stream of life appears to flow onward forever with steady current, but as a general rule it ebbs and flows in cycles, which involve a periodic rise and fall of divisional energy. The phenomena of the life-cycle are characteristic of most, perhaps all, organisms. The complete life-cycle consists of three phases or periods, namely: an adolescent period of high vitality, a mature period of balanced metabolism, and a senescent period of decline. Each life-cycle begins with the germination of the new organism and terminates with its death, and it is reproduction which constitutes the connecting link between one life-cycle and another.

Reproduction, as previously intimated, is mainly of two kinds, namely: somatogenic reproduction, which is less general and confined to the metists, and cytogenic reproduction, which is common to metists and protists, and which is the ordinary method by which new organisms originate. Reproduction is termed somatogenic, when the germ separated from the body of the parent consists of a whole mass of somatic or tissue cells not expressly set aside and specialized for reproductive purposes. Reproduction is termed cytogenic, when the germ separated from the parent or parents consists of a single cell (e.g. a spore, gamete, or zygote) dedicated especially to reproductive purposes.

Cytogenic reproduction may be either nonsexual (agamic) or sexual, according as the cell which constitutes the germ is an agamete or a gamete. An agamete is a germ cell not specialized for union with another complementary cell, or, in other words, it is a reproductive cell incapable of syngamy, e.g. a spore. A gamete, on the other hand, is a reproductive cell (germ cell) specialized for the production of a zygote (a synthetic or diploid germ cell) by union with a complementary cell, e.g. an egg, or a sperm.

Nonsexual cytogenic reproduction is of three kinds, according to the nature of the agamete. When a unicellular organism gives rise to two new individuals by simple cell-division, we have fissiparation or binary fission. When a small cell or bud is formed and separated by division from a larger parent cell, we have budding (gemmation) or unequal fission. When the nucleus of the parent cell divides many times to form a number of daughter-nuclei, which then partition the cytoplasm of the parent cell among themselves so as to form a large number of reproductive cells called spores, we have what is known as sporulation or multiple fission. The first and second kind of nonsexual reproduction are confined to the protists, but the third kind (sporulation) also occurs among the metists.

Sexual cytogenic reproduction is based upon gametes or mating germ cells. Since complementary gametes are specialized for union with each other to form a single synthetic cell, the zygote, the number of their nuclear threads or chromosomes is reduced to one half (the haploid number) at the time of maturation, so that the somatic or tissue cells of the parent organism have double the number (the diploid number) of chromosomes present in the reduced or mature gametes. Hence, when the gametes unite to form a zygote, summation is prevented and the diploid number of chromosomes characteristic of the given species of plant or animal is simply restored by the process of syngamy or union. The process by which the number of chromosomes is reduced in gametes is called meiosis, and, among the metists, it is distinct from syngamy, which, in their case, is a separate process called fertilization. Among the protists, we have, besides fertilization, another type of syngamy called conjugation, which combines meiosis with fertilization.

In sexual reproduction, we have three kinds of gametes, namely: isogametes, anisogametes, and heterogametes. In the type of sexual reproduction known as isogamy, the complementary gametes are exactly alike both in size and shape. There is no division of labor between them. Each of the fusing gametes is equally fitted for the double function which they must perform, namely, the kinetic function, which enables them to reach each other and unite by means of movement, and the trophic function which consists in laying up a store of food for the sustenance of the developing embryo. In anisogamy, the complementary gametes are alike in shape, but unlike in size, and here we have the beginning of that division of labor, upon which the difference of gender or sex is based. The larger or female gamete is called a macrogamete. It is specialized for the trophic rather than the kinetic function, being rendered more inert by having a large amount of yolk or nutrient material stored up within it. The smaller or male gamete is called a microgamete. It is specialized for the kinetic function, since it contains less yolk and is the more agile of the two. In anisogamy, however, the division of labor is not complete, because both functions are still retained by either gamete, albeit in differing measure. In the heterogamy, the differentiation between the male and female gametes is complete, and they differ from each other in structure as well as size. The larger or female gamete has no motor apparatus and retains only the trophic function. The kinetic function is sacrificed to the task of storing up a food supply for the embryo. Such a gamete is called a hypergamete or egg. The smaller or male gamete is known, in this case, as a hypogamete or sperm. It has a motor apparatus, but no stored-up nutrients, and has even sloughed off most of its cytoplasm, in its exclusive specialization for the motor function. In heterogamy, accordingly, the division of labor is complete.

We may distinguish two principal kinds of sexual reproduction, namely: unisexual reproduction and bisexual reproduction. When a single gamete such as an unfertilized egg gives rise (with, or without, chromosomal reduction) to a new organism, we have unisexual reproduction or parthenogenesis. Parthenogenesis from a reduced egg gives rise to an organism having only the haploid number of chromosomes, as is the case with the drone or male bee, but unreduced eggs give rise to organisms having the diploid number of chromosomes. Parthenogenesis, as we shall see presently, can, in some cases, be induced by artificial means. When reproduction takes place from a zygote or diploid germ cell formed by the union of two gametes, we have what is known as bisexual reproduction or syngamy. It is, perhaps, permissible to distinguish a third or intermediate kind of sexual reproduction, for which we might coin the term autosexual. What we refer to as autosexual reproduction is usually known as autogamy, and occurs when a diploid nucleus is formed in a germ cell by the union (or, we might say, reunion) of two daughter-nuclei derived from the same mother-nucleus. Autogamy occurs not only among the protists (e. g. Amœba albida), but also among the metists, as is the case with the brine shrimp, Artemia salina, in which the diploid number of chromosomes is restored after reduction by a reunion of the nucleus of the second polar body with the reduced nucleus of the egg. Autogamy is somewhat akin to kleistogamy, which occurs among hermaphroditic metists of both the plant and animal kingdoms. The violet is a well-known example. In kleistogamy or self-fertilization, the zygote is formed by the union of two gametes derived from the same parent organism. Strictly speaking, however, kleistogamy is not autogamy, but syngamy, and must, therefore, be classed as bisexual reproduction. It is, of course, necessarily confined to hermaphrodites.

Loeb’s experiments in artificial parthenogenesis have been sensationally misinterpreted by some as an artificial production of life. What Jacques Loeb really did was to initiate development in an unfertilized egg by the use of chemical and physical excitants. The writer has repeated these experiments with the unfertilized eggs of the common sea urchin, Arbacia punctulata, using very dilute butyric acid and hypertonic sea water as stimulants. Cleavage had started within an hour and a half after the completion of the aforesaid treatment, and the eggs were in the gastrula stage by the following morning (9 hours later). In three days, good specimens of the larval stage known as the pluteus could be found swimming in the normal sea water to which the eggs had been transferred from the hypertonic solution. Since mature sea urchin eggs undergo reduction before insemination takes place, the larval sea urchins arising from these artificially activated eggs had the reduced or haploid number of chromosomes instead of the diploid number possessed by normal larvæ arising from eggs activated by the sperm. For, in fertilization, the sperm not only activates the egg, but is also the means of securing biparental inheritance, by contributing its quota of chromosomes to the zygotic complex. Hence, it is only in the former function, i. e. of initiating cleavage in the egg, that a chemical excitant can replace the sperm. In any case, it is evident that these experiments do not constitute an exception to the law of genetic cellular continuity. The artificially activated egg comes from the ovaries of a living female sea urchin, and in this there is small consolation for the exponent of abiogenesis. The terse comment of an old Irish Jesuit sizes up the situation very aptly: “The Blue Flame Factory,” he said, “has announced another discovery of the secret of life. A scientist made an egg and hatched an egg. The only unfortunate thing was that the egg he hatched was not the egg he made.” How an experiment of this sort could be interpreted as an artificial production of life is a mystery. The only plausible explanation is that given by Professor Wilson, who traces it to the popular superstition that the egg is a lifeless substrate, which is animated by the sperm. The idea owes its origin to the spermists of the 17th century, who defended this doctrine against the older school of preformationists known as ovists. It is now, however, an embryological commonplace that egg and sperm are both equally cellular, equally protoplasmic, and equally vital.

The phenomena of the life-cycle in organisms find their explanation in what, perhaps, is inherent in all living matter, namely, a tendency to involution and senescence. This tendency, in the absence of a remedial process of rejuvenation, leads inevitably to death. Living matter seems to “run down” like a clock, and to stand in similar need of a periodic “rewinding.” This reinvigoration of protoplasm is accomplished by means of several different types of nuclear reorganization. Since no nuclear reorganization occurs in somatogenic reproduction, there seem to be limits to this type of propagation. Plants, like the potato and the apple, cannot be propagated indefinitely by means of tubers, shoots, stems, etc. The stock plays out in time, and, ever and anon, recourse must be had to seedlings. Hence a process of nuclear reorganization seems, in most cases, at least, to be essential for the restoration of vitality and the continuance of life. Whether this need of periodic renewal is absolutely universal, we cannot say. The banana has been propagated for over a century by the somatogenic method, and there are a few other instances in which there appears to be no limit to this type of reproduction. Nevertheless, the tendency to decline is so common among living beings that the rare exceptions serve only to confirm (if they do not follow) the general rule.

In cytogenic reproduction three kinds of rejuvenation by means of nuclear reorganization are known: (1) amphimixis or syngamy; (2) automixis or autogamy; (3) endomixis. In amphimixis or syngamy, two gametic (haploid) nuclei of different parental lineage are commingled to form the diploid nucleus of the zygote, which is consequently of biparental origin. In automixis or autogamy, two reduced or haploid nuclei of the same parental lineage unite to form a diploid nucleus, the uniting nuclei being daughter-nuclei derived from a common parent nucleus. In endomixis, the nucleus of the exhausted cell disintegrates and fuses with the cytoplasm, out of which it is reformed or reconstructed as the germinal nucleus of a rejuvenated cellular series. Endomixis occurs as a periodic phenomenon among the protists, and it appears to be homologous with parthenogenesis among metists. In certain ciliates, like the Paramœcium, endomixis and syngamy are facultative methods of rejuvenation. This has been proved most conclusively by Professor Calkins’ work on Uroleptus mobilis, an organism in which both endomixis and conjugation are amenable to experimental control. Nonsexual reproduction in this protozoan (by binary fission) is attended with a gradual weakening of metabolic activity, which increases with each successive generation. The initial rate of division and metabolic energy can, however, be restored either by conjugation (of two individuals), or by endomixis, which takes place (in a single individual) during encystment. The race, however, inevitably dies out, if both encystment and conjugation are prevented. Even in such protists as do not exhibit the phenomenon of nuclear reorganization through sexual reproduction, Kofoid points to the phenomenon of alternating periods of rest and rapid cell-division as evidence that some process of periodically-recurrent nuclear organization must exist in the organisms, which do not conjugate. This process of nuclear reorganization manifested by periodic spurts of renewed divisional energy is, according to Kofoid, a more primitive mode of rejuvenation than endomixis. “The phenomenon of endomixis,” he says, “appears to be somewhat more like that of parthenogenesis than a more primitive form of nuclear reorganization.” (Science, April 6, 1923, p. 403.) At all events, it seems safe to conclude that the tendency to senescence is pretty general among living organisms, and that this tendency, unless counteracted by a periodic reorganization of the nuclear genes, results inevitably in the deterioration and final extinction of the race.

In this inexhaustible power of self-renewal inherent in all forms of organic life, the mechanist and the upholder of abiogenesis encounter an insuperable difficulty. In inorganic nature, where the perpetual-motion device is a chimera, and the law of entropy reigns in unchallenged supremacy, nothing analogous to it can be found. The activity of all non-living units of nature, from the hydrogen atom to the protein multimolecule, is rigidly determined by the principle of the degradation of energy. The inorganic unit cannot operate otherwise than by externalizing and dissipating irreparably its own energy-content. Nor is its reconstruction and replenishment with energy ever again possible except through the wasteful expenditure of energy borrowed from some more richly endowed inorganic unit. In order to pay Paul a little, Peter must be robbed of much. Wheresoever atoms are built up into complex endothermic molecules, the constructive process is rigidly dependent upon the administration thereto of external energy, which in the process of absorption must of necessity fall from a higher level of intensity. And when the energy thus absorbed by the complex molecule is again set free by combustion, it is degraded to a still lower potential, from which, without external intervention, it can never rise again to its former plane of intensity. The phenomena of radioactivity tell the same tale. All the heavier atoms, at least, are constantly disintegrating with a concomitant discharge of energy. There is no compensating process, however, enabling such an atom to re-integrate and recharge itself at stated intervals; and, once it has broken down into its component protons and electrons, “not all the king’s horses nor all the king’s men can ever put Humpty-Dumpty together again.” In a word, none of the inorganic units of the mineral world exhibits that wonderful power of autonomous recuperation which a unicellular ciliate manifests when it rejuvenates itself by means of endomixis. The inorganic world knows of no constructive process comparable to this. It is only in living beings that we find what James Ward describes as the “tendency to disturb existing equilibria, to reverse the dissipative processes which prevail throughout the inanimate world, to store and build up where they are ever scattering and pulling down, the tendency to conserve individual existence against antagonistic forces, to grow and to progress, not inertly taking the easier way but seemingly striving for the best, retaining every vantage secured, and working for new ones.” (“On the Conservation of Energy,” I, p. 285.)

Summing up, then, we have seen that the reproductive process, whereby the metists or multicellular organism originate, resolves itself ultimately into a process of cell-division. The same is true of the protists or unicellular organisms. For all cells, whether they be protists, germ cells, or somatic cells, originate in but one way, and that is, from a preëxistent living cell by means of cell-division. Neither experimentation nor observation has succeeded in revealing so much as a single exception to the universal law of genetic cellular continuity, and the hypothesis of spontogenesis is outlawed, in consequence, by the logic of scientific induction. Even the hope that future research may bring about an amelioration of its present status is entirely unwarranted in view of the manifest dynamic superiority of the living organism as compared with any of the inert units of the inorganic world. “Whatever position we take on this question,” says Edmund B. Wilson, in the conclusion of his work on the Cell, “the same difficulty is encountered; namely, the origin of that coördinated fitness, that power of active adjustment between internal and external relations, which, as so many eminent biological thinkers have insisted, overshadows every manifestation of life. The nature and origin of this power is the fundamental problem of biology. When, after removing the lens of the eye in the larval salamander, we see it restored in perfect and typical form by regeneration from the posterior layer of the iris, we behold an adaptive response to changed conditions of which the organism can have no antecedent experience either ontogenetic or phylogenetic, and one of so marvelous a character that we are made to realize, as by a flash how far we still are from a solution of this problem.” Then, after discussing the attempt of evolutionists to bridge the enormous gap that separates living, from lifeless nature, he continues: “But when all these admissions are made, and when the conserving action (sic) of natural selection is in the fullest degree recognized, we cannot close our eyes to two facts: first, that we are utterly ignorant of the manner in which the idioplasm of the germ cell can so respond to the influence of the environment as to call forth an adaptive variation; and second, that the study of the cell has on the whole seemed to widen rather than to narrow the enormous gap that separates even the lowest forms of life from the inorganic world.” (“The Cell,” 2nd edit., pp. 433, 434.)

§ 5. A “New” Theory of Abiogenesis

Since true science is out of sympathy with baseless conjectures and gratuitous assumptions, one would scarcely expect to find scientists opposing the inductive trend of the known facts by preferring mere possibilities (if they are even such) to solid actualities. As a matter of fact, however, there are not a few who obstinately refuse to abandon preconceptions for which they can find no factual justification. The bio-chemist, Benjamin Moore, while conceding the bankruptcy of the old theory of spontaneous generation, which looked for a de novo origin of living cells in sterilized cultures, has, nevertheless, the hardihood to propose what he is pleased to term a new one. Impressed by the credulity of Charlton Bastian and the autocratic tone of Schäfer, he sets out to defend as plausible the hypothesis that the origination of life from inert matter may be a contemporaneous, perhaps, daily, phenomenon, going on continually, but invisible to us, because its initial stages take place in the submicroscopic world. By the time life has emerged into the visible world, it has already reached the stage at which the law of genetic continuity prevails, but at stages of organization, which lie below the limit of the microscope, it is not impossible, he thinks, that abiogenesis may occur. To plausibleize this conjecture, he notes that the cell is a natural unit composed of molecules as a molecule is a natural unit composed of atoms. He further notes, that, in addition to the cell, there is in nature another unit higher than the monomolecule, namely, the multimolecule occurring in both crystalloids and colloids. The monomolecule consists of atoms held together by atomic valence, whereas the multimolecule consists of molecules whose atomic valence is completely saturated, and which are, consequently, held together by what is now known as molecular or residual valence. Moore cites the crystal units of sodium bromide and sodium iodide as instances of multimolecules. The crystal unit of ordinary salt, sodium chloride, is an ordinary monomolecule, with the formula NaCl. In the case of the former salts the crystal units consist of multimolecules of the formula NaB·(H₂O)₂ and NaI·(H₂O)₂, the water of crystallization not being mechanically confined in the crystals, but combined with the respective salt in the exact ratio of two molecules of water to one of the salt. Judged by all chemical tests, such as heat of formation, the law of combination in fixed ratios, the manifestation of selective affinity, etc., the multimolecule is quite as much entitled to be considered a natural unit as is the monomolecule.

But it is not in the crystalloidal multimolecule, but in the larger and more complex multimolecule of colloids (viscid substances like gum arabic, gelatine, agar-agar, white of egg, etc.), that Moore professes to see a sort of intermediate between the cell and inorganic units. Such colloids form with a dispersing medium (like water) an emulsion, in which the dispersed particles, known as ultramicrons or “solution aggregates,” are larger than monomolecules. It is among these multimolecules of colloids that Moore would have us search for a transitional link connecting the cell with the inorganic world. Borrowing Herbert Spencer’s dogma of the complication of homogeneity into heterogeneity, he asserts that such colloidal multimolecules would tend to become more and more complex, and consequently more and more instable, so that their instability would gradually approach the chronic instability or constant state of metabolic fluxion manifest in living organisms. The end-result would be a living unit more simply organized than the cell, and evolution seizing upon this submicroscopic unit would, in due time, transform it into cellular life of every variety and kind. Ce n’est que le premier pas qui coûte!

It should be noted that this so-called law is a mere vague formula like the “law” of natural selection and the “law” of evolution. The facts which it is alleged to express are not cited, and its terms are far from being quantitative. It is certainly not a law in the sense of Arrhénius, who says: “Quantitative formulation, that is, the establishing of a connection, expressed by a formula, between different quantitatively measurable magnitudes, is the peculiar feature of a law.” (“Theories of Chemistry,” Price’s translation, p. 3.) Now, chemistry, as an exact science, has no lack of laws of this kind, but no branch of chemistry, whether physical, organic, or inorganic, knows of any law of complexity, that can be stated in either quantitative, or descriptive, terms. We will, however, let Moore speak for himself:

“It may then be summed up as a general law universal in its application to all matter, ... a law which might be called the Law of Complexity, that matter so far as its energy environment will permit tends to assume more and more complex forms in labile equilibrium. Atoms, molecules, colloids, and living organisms, arise as a result of the operations of this law, and in the higher regions of complexity it induces organic evolution and all the many thousands of living forms....

“In this manner we can conceive that the hiatus between non-living and living things can be bridged over, and there awakens in our minds the conception of a kind of spontaneous production of life of a different order from the old. The territory of this spontaneous generation of life lies not at the level of bacteria, or animalculæ, springing forth into life from dead organic matter, but at a level of life lying deeper than anything the microscope can reveal, and possessing a lower unit than the living cell, as we form our concept of it from the tissues of higher animals and plants.

“In the future, the stage at which colloids begin to be able to deal with external energy forms, such as light, and build up in chemical complexity, will yield a new unit of life opening a vista of possibilities as magnificent as that which the establishment of the cell as a unit gave, with the development of the microscope, about a century ago.” (“Origin and Nature of Life,” pp. 188-190.)

Having heard out a rhapsody of this sort, one may be pardoned a little impatience at such a travesty on science. Again we have the appeal from realities to fancies, from the seen to unseen. Moore sees no reason to doubt and is therefore quite sure that an unverified occurrence is taking place “at a level of life lying deeper than anything the microscope can reveal.” The unknown is a veritable paradise for irresponsible speculation and phantasy. It is well, however, to keep one’s feet on the terra firma of ascertained facts and to make one’s ignorance a motive for caution rather than an incentive to reckless dogmatizing.

To begin with, it is not to a single dispersed particle or ultramicron that protoplasm has been likened, but to an emulsion, comprising both the dispersed particles and the dispersing medium, or, in other words, to the colloidal system as a whole. Moreover, even there the analogy is far from being perfect, and is confined exclusively, as Wilson has pointed out, to a rough similarity of structure and appearance. The colloidal system is obviously a mere aggregate and not a natural unit like the cell, and its dispersed particles (ultramicrons) do not multiply and perpetuate themselves by growth and division as do the living components or formed bodies of the cell. As for the single ultramicron or multimolecule of a colloidal solution, it may, indeed, be a natural unit, but it only resembles the cell in the sense that, like the latter, it is a complex of constituent molecules. Here, however, all resemblance ceases; for the ultramicron does not display the typically vital power of self-perpetuation by growth and division, which, as we have seen, is characteristic not only of the cell as a whole, but of its single components or organelles. Certainly, the distinctive phenomena of colloidal systems cannot be interpreted as processes of multiplication. There is nothing suggestive of this vital phenomenon in the reversal of phase, which is caused by the addition of electrolytes to oil emulsions, or in gelation, which is caused by a change of temperature in certain hydrophilic colloids. Thus the addition of the salt of a bivalent cation (e.g. CaCl₂ or BaCl₂) to an oil-in-water emulsion (if soap is used as the emulsifier) will cause the external or continuous phase (water) to become the internal or discontinuous phase. Vice versa, a water-in-oil emulsion can be reversed into an oil-in-water emulsion, under the same conditions, by the addition of the salt of a monovalent cation (e. g. NaOH). Solutions of hydrophilic colloids, like gelatine or agar-agar, can be made to “set” from the semifluid state of a hydrosol into the semisolid state of a hydrogel, by lowering the temperature, after which the opposite effect can be brought about by again raising the temperature. In white of egg, however, once gelation has taken place, through the agency of heat, it is impossible to reconvert the “gel” into a “sol” (solution). In such phenomena, it is, perhaps, possible to see a certain parallelism with some processes taking place in the cell, e. g. the osmotic processes of absorption and excretion, but to construe them as evidence of propagation by growth and division would be preposterous.

Nor is the subterfuge of relegating the question to the obscurity of the submicroscopic world of any avail; for, as a matter of fact, submicroscopic organisms actually do exist, and manage, precisely by virtue of this uniquely vital power of multiplication or reproductivity, to give indirect testimony of their invisible existence. The microörganisms, for example, which cause the disease known as Measles are so minute that they pass through the pores of a porcelain filter, and are invisible to the highest powers of the microscope. Nevertheless, they can be bred in the test tube cultures of the bacteriologist, where they propagate themselves for generations without losing the definite specificity, which make them capable of producing distinctive pathological effects in the organisms of higher animals, including man. Each of these invisible disease germs communicates but one disease, with symptoms that are perfectly characteristic and definite. Moreover, they are specific in their choice of a host, and will not infect any and every organism promiscuously. Finally, they never arise de novo in a healthy host, but must always be transmitted from a diseased to a healthy individual. The microscopist is tantalized, to quote the words of Wilson, “with visions of disease germs which no eye has yet seen, so minute as to pass through a fine filter, yet beyond a doubt self-perpetuating and of specific type.” (Science, March 9, 1923, p. 283.) Submicroscopic dimensions, therefore, are no obstacle to the manifestation of such vital properties as reproduction, genetic continuity, and typical specificity; and we must conclude that, if any of the ultramicrons of colloids possessed them, their minute size would not debar them from manifesting the fact. As it is, they fail to show any vital quality, whereas the submicroscopic disease germs give evidence of possessing all the characteristics of visible cells.

In fine, the radical difference between inorganic units, like atoms, molecules, and multimolecules, and living units, like protozoans and metazoans, is so obvious that it is universally admitted. Not all, however, are in accord when it comes to assigning the fundamental reason for the difference in question. Benjamin Moore postulates a unique physical energy, peculiar to living organisms and responsible for all distinctively vital manifestations. This unique form of energy, unlike all other forms, he calls “biotic energy,” denying at the same time that it is a vital force. (Cf. op. cit., pp. 224-226.) Moore seems to be desirous of dressing up vitalism in the verbal vesture of mechanism. He wants the game, without the name. But, if his “biotic energy” is unlike all other forms of energy, it ought not to parade under the same name, but should frankly call itself a “vital force.” Somewhat similar in nature is Osborn’s suggestion that the peculiar properties of living protoplasm may be due to the presence of a unique chemical element called Bion. (Cf. “The Origin and Evolution of Life,” 1917, p. 6.) Now, a chemical element unlike other chemical elements is not a chemical element at all. Osborn’s Bion, like Moore’s biotic energy, ought, by all means, to make up its mind definitely on Hamlet’s question of “to be, or not to be.” The policy of “It is, and it is not,” is not likely to win the approval of either mechanists or vitalists.

§ 6. Hylomorphism versus Mechanism and Neo-vitalism

Mechanism and Neo-vitalism represent two extreme solutions of this problem of accounting for the difference between living and lifeless matter. Strictly speaking, it is an abuse of language to refer to mechanism as a solution at all. Its first pretense at solving the problem is to deny that there is any problem. But facts are facts and cannot be disposed of in this summary fashion. Forced, therefore, to face the actual fact of the uniqueness of living matter, mechanists concede the inadequacy of their physicochemical analogies, but obstinately refuse to admit the legitimacy of any other kind of explanation. Confronted with realities, which simply must have some explanation, they prefer to leave them unexplained by their own theory than have them explained by any other. They recognize the difference between a living animal and a dead animal (small credit to them for their perspicacity!), but deny that there is anything present in the former which is not present in the latter.

Neo-vitalism, on the other hand, is, at least, an attempt at solving the problem in the positive sense. It ascribes the unique activities of living organisms to the operation of a superphysical and superchemical energy or force resident in living matter. This unique dynamic principle is termed vital force. It is not an entitive nor a static principle, but belongs to the category of efficient or active causes, being variously described as an agent, energy, or force. To speak precisely, the term agent denotes an active being or substance; the term energy denotes the proximate ground in the agent of a specific activity; while the term force denotes the activity or free, kinetic, or activated phase of a given energy. In practice, however, these terms are often used interchangeably. Thus Driesch, who, like all other Neo-vitalists, makes the vital principle a dynamic factor rather than an entitive principle, refers to the vital principle as a “non-material,” “non-spatial” agent, though the term energy would be more precise. To this active or dynamic vital principle Driesch gives a name, which he borrowed from Aristotle, that is, entelechy. In so doing, however, he perverted, as he himself confesses, the true Aristotelian sense of the term in question: “The term,” he says, “... is not here used in the proper Aristotelian sense.” (“History and Theory of Vitalism,” p. 203.) His admission is quite correct. At the critical point, Driesch, for all his praise of Aristotle, deserts the Stagirite and goes over to the camp of Plato, Descartes, and the Neo-vitalists!

Driesch’s definition is as follows: “Entelechy is an agent sui generis, non-material and non-spatial, but acting ‘into’ space.” (Op. cit., p. 204.) Aristotle’s use of the term in this connection is quite different. He uses it, for example, in a static, rather than a dynamic, sense: “The term ‘entelechy,’” he says, “is used in two senses; in one it answers to knowledge, in the other to the exercise of knowledge. Clearly in this case it is analogous to knowledge.” (“Peri Psyches,” Bk. II, c. 1.) Knowledge, however, is only a second or static entelechy. Hence, in order to narrow the sense still further Aristotle refers to the soul as a first entelechy, by which he designates a purely entitive principle, that is, a constituent of being or substance (cf. op. cit. ibidem). The first, or entitive, entelechy, therefore, is to be distinguished from all secondary entelechies, whether of the dynamic order corresponding to kinetic energy or force, or of the static order corresponding to potential energy. Neither is it an agent, because it is only a partial constituent of the total agent, that is, of the total active being or substance. Hence, generally speaking, that which acts (the agent) is not entelechy, but the total composite of entelechy and matter, first entelechy being consubstantial with matter and not a separate existent or being. In fine, according to Aristotelian philosophy, entelechy (that is, “first” or “prime” entelechy) is not an agent nor an energy nor a force. In other words, it is totally removed from the category of efficient or active causes. The second difference between Driesch and Aristotle with respect to the use of the term entelechy lies in the fact that Driesch uses it as a synonym for the soul or vital principle, whereas, according to Aristotle, entelechy is common to the non-living units of inorganic nature as well as the living units (organisms) of the organic world. All vital principles or souls are entelechies, but not all entelechies are vital principles. All material beings or substances, whether living or lifeless, are reducible, in the last analysis, to two consubstantial principles or complementary constituents, namely, entelechy and matter. Entelechy is the binding, type-determining principle, the source of unification and specification, which makes of a given natural unit (such as a molecule or a protozoan) a single and determinate whole. Matter is the determinable and potentially-multiple element, the principle of divisibility and quantification, which can enter indifferently into the composition of this or that natural unit, and which owes its actual unity and specificity to the entelechy which here and now informs it. It is entelechy which makes a chemical element distinct from its isobare, a chemical compound distinct from its isomer, a paramœcium distinct from an amœba, a maple distinct from an oak, and a bear distinct from a tiger.

The molecular entelechy finds expression in what the organic chemist and the stereochemist understand by valence, that is, the static aspect of valence considered as the structural principle of a molecule. Hence it is entelechy which makes a molecule of urea [O:C:(NH₂)₂] an entirely different substance from its isomer ammonium cyanate [NH₄·O·C:N], although the material substrate of each of these molecular units consists of precisely the same number and kinds of atoms. Similarly, it is the atomic entelechy which gives to the isotopes of Strontium chemical properties different from those of the isotopes of Rubidium, although the mass and corpuscular (electronic and protonic) composition of their respective atoms are identical. It is the vital entelechy or soul, which causes a fragment cut from a Stentor to regenerate its specific protoplasmic architecture instead of the type which would be regenerated from a similar fragment cut from another ciliate such as Dileptus.

In all the tridimensional units of nature, both living and non-living, the hylomorphic analysis of Aristotle recognizes an essential dualism of matter and entelechy. Hence it is not in the presence and absence of an entelechy (as Driesch contends) that living organisms differ from inorganic units. The sole difference between these two classes of units is one of autonomy and inertia. The inorganic unit is inert, not in the sense that it is destitute of energy, but in the sense that it is incapable of self-regulation and rigidly dependent upon external factors for the utilization of its own energy-content. The living unit, on the other hand, is endowed with dynamic autonomy. Though dependent, in a general way, upon environmental factors for the energy which it utilizes, nevertheless the determinate form and direction of its activity is not imposed in all its specificity by the aforesaid environmental factors. The living being possesses a certain degree of independence with respect to these external forces. It is autonomous with a special law of immanent finality or reflexive orientation, by which all the elements and energies of the living unit are made to converge upon one and the same central result, namely, the maintenance and development of the organism both in its capacity as an individual and in its capacity as the generative source of its racial type.

The entelechies of the inert units of inorganic nature turn the forces of these units in an outward direction, so that they are incapable of operating upon themselves, of modifying themselves, or of regulating themselves. They are only capable of operating upon other units outside themselves, and in so doing they irreparably externalize their energy-contents. All physicochemical action is transitive or communicable in character, whereas vital action is of the reflexive or immanent type. Mechanical action, for example, is intermolar (i.e. an exchange between large masses of inorganic matter); physical action is intermolecular; chemical action is interatomic; while in radioactive and electrical phenomena we have intercorpuscular action. Hence all the forms of activity native to the inorganic world are reducible to interaction between discontinuous and unequally energized masses or particles. Always it is a case of one mass or particle operating upon another mass or particle distinct from, and spatially external to, itself. The effect or positive change produced by the action is received into another unit distinct from the agent or active unit, which can never become the receptive subject of the effect generated by its own activity. The living being, on the contrary, is capable of operating upon itself, so that what is modified by the action is not outside the agent but within it. The reader does not modify the book, but modifies himself by his reading. The blade of grass can nourish not only a horse, but its very self, whereas a molecule of sodium nitrate is impotent to nourish itself, and can only nourish a subject other than itself, such as the blade of grass. Here the active source and receptive subject of the action is one and the same unit, namely, the living organism, which can operate upon itself in the interest of its own perfection. In chemical synthesis two substances interact to produce a third, but in vital assimilation one substance is incorporated into another without the production of a third. Thus hydrogen unites with oxygen to produce water. But in the case of assimilation the reaction may be expressed thus: Living protoplasm plus external nutriment equals living protoplasm increased in quantity but unchanged in specificity. Addition or subtraction alters the nature of the inorganic unit, but does not change the nature of the living unit. In chemical change, entelechy is the variant and matter is the constant, but in metabolic change, matter is the variant and entelechy the constant. “Living beings,” says Henderson, “preserve, or tend to preserve, an ideal form, while through them flows a steady stream of energy and matter which is ever changing, yet momentarily molded by life; organized, in short.” (“Fitness of the Environment,” 1913, pp. 23, 24.) The living unit maintains its own specific type amid a constant flux of matter and flow of energy. It subjugates the alien substances of the inorganic world, eliminates their mineral entelechies and utilizes their components and energies for its own purposes. The soul or vital entelechy, therefore, is more powerful than the entelechies of inorganic units which it supplants. It turns the forces of living matter inward, so that the living organism becomes capable of self-regulation and of striving for the attainment of self-perfection. It is this reflexive orientation of all energies towards self-perfection that is the unique characteristic of the living being, and not the nature of the energies themselves. The energies by which vital functions are executed are the ordinary physicochemical energies, but it is the vital entelechy or soul which elevates them to a higher plane of efficiency and renders them capable of reflexive or vital action. There is, in short, no such thing as a special vital force. The radical difference between living and non-living units does not consist in the possession or non-possession of an entelechy, nor yet in the peculiar nature of the forces displayed in the execution of vital functions, but solely in the orientation of these forces towards an inner finality.

§ 7. The Definition of Life

Life, then, may be defined as the capacity of reflexive or self-perfective action. In any action, we may distinguish four things: (1) the agent, or source of the action; (2) the activity or internal determination differentiating the agent in the active state from the selfsame agent in the inactive state; (3) the patient or receptive subject; (4) the effect or change produced in the patient by the agent. Let us suppose that a boy named Tom kicks a door. Here Tom is the agent, the muscular contraction in his leg is the activity, the door is the patient or recipient, while the dent produced in the door is the effect or change of which the action is a production. In this action, the effect is produced not in the cause or agent, but in a patient outside of, and distinct from, the agent, and the otherness of cause and effect is consequently complete. Such an action is termed transitive, which is the characteristic type of physicochemical action. In another class of actions, however, (those, namely, that are peculiar to living beings) the otherness of cause and effect is only partial and relative. When the agent becomes ultimately the recipient of the effect or modification wrought by its own activity, that is, when the positive change produced by the action remains within the agent itself, the action is called immanent or reflexive action. Since, however, action and passion are opposites, they can coëxist in the same subject only upon condition that said subject is differentiated into partial otherness, that is, organized into a plurality of distinct and dissimilar parts or components, one of which may act upon another. Hence only the organized unit or organism, which combines unity or continuity of substance with multiplicity and dissimilarity of parts is capable of immanent action. The inorganic unit is capable only of transitive action, whose effect is produced in an exterior subject really distinct from the agent. The living unit or organism, however, is capable of both transitive action and immanent (reflexive) action. In such functions as thought and sensation, the living agent modifies itself and not an exterior patient. In the nutritive or metabolic function the living being perfects itself by assimilating external substances to itself. It develops, organizes, repairs, and multiplies itself, holding its own and perpetuating its type from generation to generation.

Life, accordingly, is the capacity of tending through any form of reflexive action to an ulterior perfection of the agent itself. This capacity of an agent to operate of, and upon, itself for the acquisition of some perfection exceeding its natural equilibrial state is the distinctive attribute of the living being. Left to itself, the inorganic unit tends exclusively to conservation or to loss, never to positive acquisition in excess of equilibrial exigencies; what it acquires it owes exclusively to the action of external factors. The living unit, on the contrary, strives in its vital operations to acquire something for itself, so that what it gets it owes to itself and not (except in a very general sense) to the action of external factors. All the actions of the living unit, both upon itself and upon external matter, result sooner or later in the acquisition on the part of the agent of a positive perfection exceeding and transcending the mere exigencies of equilibration. The inorganic agent, on the contrary, when in the state of tension, tends only to return to the equilibrial state by alienation or expenditure of its energy; otherwise, it tends merely to conserve, by virtue of inertia, the state of rest or motion impressed upon it from without. In the chemical changes of inorganic units, the tendency to loss is even more in evidence. Such changes disrupt the integrity of the inorganic unit and dissipate its energy-content, and the unit cannot be reconstructed and recharged, except at the expense of a more richly endowed inorganic unit. The living organism, however, as we see in the case of the paramæcium undergoing endomixis, is capable of counteracting exhaustion by recharging itself.

The difference between transitive and reflexive action is not an accidental difference of degree, but an essential difference of kind. In reflexive actions, the source of the action and the recipient of the effect or modification produced by it are one and the same substantial unit or being. In transitive actions, the receptive subject of the positive change is an alien unit distinct from the unit, which puts forth the action. Hence a reflexive action is not an action which is less transitive; it is an action which is not at all transitive, but intransitive. The difference, therefore, between the living organism, which is capable of both reflexive and transitive action, and the inorganic unit, which is only capable of transitive action, is radical and essential. This being the case, an evolutionary transition from an inert multimolecule to a reflexively-operating cell or cytode, becomes inconceivable. Evolution might, at the very most, bring about intensifications and combinations of the transitive agencies of the physicochemical world, but never the volte face, which would be necessary to reverse the centrifugal orientation of forces characteristic of the inorganic unit into the centripetal orientation of forces which makes the living unit capable of self-perfective action, self-regulation, and self-renewal. The idea, therefore, of a spontaneous derivation of living units from lifeless colloidal multimolecules must be rejected, not merely because it finds no support in the facts of experience, but also because it is excluded by aprioristic considerations.

§ 8. An Inevitable Corollary

But, if inorganic matter is impotent to vitalize itself by means of its native physicochemical forces, the inevitable alternative is that the initial production of organisms from inorganic matter was due to the action of some supermaterial agency. Certain scientists, like Henderson of Harvard, while admitting the incredibility of abiogenesis, prefer to avoid open conflict with mechanism and materialism by declaring their neutrality. “But while biophysicists like Professor Schäfer,” says Henderson, “follow Spencer in assuming a gradual evolution of the organic from the inorganic, biochemists are more than ever unable to perceive how such a process is possible, and without taking any final stand prefer to let the riddle rest.” (“Fitness of the Environment,” p. 310, footnote.) Not to take a decisive stand on this question, however, is tantamount to making a compromise with what is illogical and unscientific; for both logic and the inductive trend of biological facts are arrayed against the hypothesis of spontaneous generation.

In the first place, it is manifest that organic life is neither self-explanatory nor eternal. Hence it must have had its origin in the action of some external agency. Life as it exists today depends upon the precedence of numerous unbroken chains of consecutive cells that extend backward into a remote past. It is, however, a logical necessity to put an end to this retrogradation of the antecedents upon which the actual existence of our present organisms depends. The infinite cannot be spanned by finite steps; the periodic life-process could not be relayed through an unlimited temporal distance; and a cellular series which never started would never arrive. Moreover, we do not account for the existence of life by extending the cellular series interminably backward. Each cell in such a series is derived from a predecessor, and, consequently, no cell in the series is self-explanatory. When it comes to accounting for its own existence, each cell is a zero in the way of explanation, and adding zeros together indefinitely will never give us a positive total. Each cell refers us to its predecessor for the explanation of why it exists, and none contains within itself the sufficient explanation of its own existence. Hence increasing even to infinity the number of these cells (which fail to explain themselves) will give us nothing else but a zero in the way of explanation. If, therefore, the primordial cause from which these cellular chains are suspended is not the agency of the physicochemical forces of inorganic nature, it follows that the first active cause of life must have been a supermaterial and extramundane agency, namely, the Living God and Author of Life.

As a matter of fact, no one denies that life has had a beginning on our globe. The physicist teaches that a beginning of our entire solar system is implied in the law of the degradation of energy, and various attempts have been made to determine the time of this beginning. The older calculations were based on the rate of solar radiation; the more recent ones, however, are based on quantitative estimates of the disintegration products of radioactive elements. Similarly, the geologist and the astronomer propound theories of a gradual constitution of the cosmic environment, which organic life requires for its support, and all such theories imply a de novo origin or beginning of life in the universe. Thus the old nebular hypothesis of Laplace postulated a hot origin of our solar system incompatible with the coëxistence of organic life, which, as the experiments of Pasteur and others have shown, is destroyed, in all cases, at a temperature just above 45° Centigrade (113° Fahrenheit). Even the enzymes or organic catalysts, which are essential for bio-chemical processes, are destroyed at a temperature between 60° and 70° Centigrade. This excludes the possibility of the contemporaneousness of protoplasm and inorganic matter, and points to a beginning of life in our solar system. Moreover, independently of this theory, the geologist sees in the primitive crystalline rocks (granites, diorites, basalts, etc.) and in the extant magmas of volcanoes evidences of an azoic age, during which temperatures incompatible with the survival of even the blue-green algæ or the most resistent bacterial spores must have prevailed over the surface of the globe. In fact, it is generally recognized by geologists that the igneous or pyrogenic rocks, which contain no fossils, preceded the sedimentary or fossiliferous rocks. The new planetesimal hypothesis, it is true, is said to be compatible with a cold origin of the universe. Nevertheless, this theory assumes a very gradual condensation of our cosmos out of dispersed gases and star dust, whereas life demands as the sine qua non condition of its existence a differentiated environment consisting of a lithosphere, a hydrosphere, and an atmosphere. Hence, it is clear that life did not originate until such an appropriate environment was an accomplished fact. All theories of cosmogony, therefore, point to a beginning of life subsequent to the constitution of the inorganic world.

Now, it is impossible for organic life to antecede itself. If, therefore, it has had a beginning in the world, it must have had a first active cause distinct from itself; and the active cause, in question, must, consequently, have been either something intrinsic, or something extrinsic, to inorganic matter. The hypothesis, however, of a spontaneous origin of life through the agency of forces intrinsic to inorganic matter is scientifically untenable. Hence it follows that life originated through the action of an immaterial or spiritual agent, namely, God, seeing that there is no other assignable agency capable of bringing about the initial production of life from lifeless matter.

§ 9. Futile Evasions

Many and various are the efforts made to escape this issue. One group of scientists, for example, attempt to rid themselves of the difficulty by diverting our attention from the problem of a beginning of organic life in the universe to the problem of its translation to a new habitat. This legerdemain has resulted in the theories of cosmozoa or panspermia, according to which life originates in a favorable environment, not by reason of spontaneous generation, but by reason of importation from other worlds. This view has been presented in two forms: (1) the “meteorite” theory, which represents the older view held by Thomson and Helmholtz; (2) the more recent theory of “cosmic panspermia” advocated by Svante Arrhénius, with H. E. Richter and F. J. Cohn as precursors. Sir Wm. Thompson suggested that life might have been salvaged from the ruins of other worlds and carried to our own by means of meteorites or fragments thrown off from life-bearing planets that had been destroyed by a catastrophic collision. These meteorites discharged from bursting planets might carry germs to distant planets like the earth, causing them to become covered with vegetation. Against this theory stands the fatal objection that the transit of a meteorite from the nearest stellar system to our own would require an interval of 60,000,000 years. It is incredible that life could be maintained through such an enormous lapse of time. Even from the nearest planet to our earth the duration of the journey would be 150 years. Besides, meteorites are heated to incandescence while passing through the atmosphere, and any seeds they might contain would perish by reason of the heat thus generated, not to speak of the terrific impact, which terminates the voyage of a meteorite.

Arrhénius suggests a method by which microörganisms might be conveyed through intersidereal space with far greater dispatch and without any mineral vehicle such as a meteorite. He notes that particles of cosmic dust leave the sun as a coronal atmosphere and are propelled through intervening space by the pressure of radiation until they reach the higher atmosphere of the earth (viz. at a height of 100 kilometers from the surface of the latter), where they become the electrically charged dust particles of polar auroras (v.g. the aurora borealis). The motor force, in this case, is the same as that which moves the vanes of a Crookes’ radiometer. Lebedeff has verified Clerk-Maxwell’s conceptions of this force and has demonstrated its reality by experiments. It is calculated that in the immediate vicinity of a luminous surface like that of the sun the pressure exerted by radiation upon an exposed surface would be nearly two milligrams per square centimeter. On a nontransparent particle having a diameter of 1.5 microns, the pressure of radiation would just counterbalance the force of universal gravitation, while on particles whose diameter was 0.16 of a micron, the pressure of radiation would be ten times as great as the pull of gravitation. Now bacterial spores having a diameter of O.3 to O.2 of a micron are known to bacteriologists, and the ultramicroscope reveals the presence of germs not more than O.1 of a micron in size. Hence it is conceivable that germs of such dimensions might be wafted to limits of our atmosphere, and might then be transported by the pressure of radiation to distant planets or stellar systems, provided, of course, they could escape the germicidal action of oxidation, desiccation, ultra-violet rays, etc. Arrhénius calculates that their journey from the earth to Mars would, under such circumstances, occupy a period of only 20 days. Within 80 days they could reach Jupiter, and they might arrive at Neptune on the confines of our solar system after an interval of 3 weeks. The transit to the constellation of the Centaur, which contains the solar system nearest to our own (the one, namely, whose central sun is the star Alpha), would require 9,000 years.

Recently, by means of photography with short-length light waves, the bacteria of “Foot-and-mouth disease,” invisible to the highest power microscope, have been revealed as rods about 100 submicrons (i.e. O.1 micron, or O.0001 millimeter) in length. (cf. Science, May 30, 1924, Supplement X.) Germs of this dimension could be as easily transported by radiation as the alleged electrically charged stardust in the aurora borealis. It may be of interest, however, to note, in this connection, that the most recent theory of the aurora borealis discards stardust in favor of nitrogen snow. Lars Vegard, a Norwegian professor, ascribes the peculiar greenish tint in the Northern Lights to the action of solar radiations on nitrogen snow, which he assumes to exist at an altitude of more than 60 miles above the earth. When he condensed crystals of solid nitrogen on a copper plate by freezing with liquid hydrogen, he found that these crystals, after bombardment with cathode rays, emit a light of green color, which gives the same strong green spectrum line as the spectrum of the aurora. As the solid nitrogen evaporates, it begins to emit the reddish light characteristic of nitrogen gas. This phenomenon would explain the changes of color that occur in the aurora borealis. (cf. Science, April 18, 1924, Suppl. X.)

Arrhénius’ theory, however, that “life is an eternal rebeginning” explains nothing and leaves us precisely where we were. In the metaphysical as well as the scientific sense, it is an evasion and not a solution. To the logical necessity of putting an end to the retrogradation of the subalternate conditions, upon which the realities of the present depend for their actual existence, we have already adverted. Moreover, the reasons which induce the scientist to postulate a beginning of life in our world are not based on any distinctive peculiarity of that world, but are universally applicable, it being established by the testimony of the spectroscope that other worlds are not differently constituted than our own. Hence Schäfer voices the general attitude of scientific men when he says: “But the acceptance of such theories of the arrival of life on earth does not bring us any nearer to a conception of its actual mode of origin; on the contrary, it merely serves to banish the investigation of the question to some conveniently inaccessible corner of the universe and leaves us in the unsatisfactory condition of affirming not only that we have no knowledge as to the mode of origin of life—which is unfortunately true—but that we never can acquire such knowledge—which it is to be hoped is not true. Knowing what we know, and believing what we believe, ... we are, I think (without denying the possibility of the existence of life in other parts of the universe), justified in regarding these cosmic theories as inherently improbable.” (Dundee Address of 1912, cf. Smithson. Inst. Rpt. for 1912, p. 503.)

Dismissing, therefore, all evasions of this sort, we may regard as scientifically established the conclusion that, so far as our knowledge goes, inorganic nature lacks the means of self-vivification, and that no inanimate matter can become living matter without first coming under the influence of matter previously alive. Given, therefore, that the conditions favorable to life did not always prevail in our cosmos, it follows that life had a beginning, for which we are obliged to account by some postulate other than abiogenesis. This conclusion seems inescapable for those who concede the scientific absurdity of spontaneous generation, but, by some weird freak of logic, not only is it escaped, but the very opposite conclusion is reached through reasoning, which the exponents are pleased to term philosophical, as distinguished from scientific, argumentation. The plight of these “hard-headed worshippers of fact,” who plume themselves on their contempt for “metaphysics,” is sad indeed. Worsted in the experimental field, they appeal the case from the court of facts to that aprioristic philosophy. “Physic of metaphysic begs defence, and metaphysic calls for aid on sense!”

Life, they contend, either had no beginning or it must have begun in our world as the product of spontaneous generation. But all the scientific theories of cosmogony exclude the former alternative. Consequently, not only is it not absurd to admit spontaneous generation, but, on the contrary, it is absurd not to admit it. It is in this frame of mind that August Weismann is induced to confide to us “that spontaneous generation, in spite of all the vain attempts to demonstrate it, remains for me a logical necessity.” (“Essays,” p. 34, Poulton’s Transl.) The presupposition latent in all such logic is, of course, the assumption that nothing but matter exists; for, if the possibility of the existence of a supermaterial agency is conceded, then obviously we are not compelled by logical necessity to ascribe the initial production of organic life to the exclusive agency of the physicochemical energies inherent in inorganic matter. Weismann should demonstrate his suppressed premise that matter coincides with reality and that spiritual is a synonym for nonexistent. Until such time as this unverified and unverifiable affirmation is substantiated, the philosophical proof for abiogenesis is not an argument at all, it is dogmatism pure and simple.

But, they protest, “To deny spontaneous generation is to proclaim a miracle” (Nägeli), and natural science cannot have recourse to “miracles” in explaining natural phenomena. For the “scientist,” miracles are always absurd as contradicting the uniformity of nature, and to recur to them for the solution of a scientific problem is, to put it mildly, distinctly out of the question. Hence Haeckel regards spontaneous generation as more than demonstrated by the bare consideration that no alternative remains except the unspeakable scientific blasphemy implied in superstitious terms like “miracle,” “creation,” and “supernatural.” For a “thinking man,” the mere mention of these abhorrent words is, or ought to be, argument enough. “If we do not accept the hypothesis of spontaneous generation,” Haeckel expostulates, “we must have recourse to the miracle of a supernatural creation.” (Italics his—“History of Creation,” I, p. 348, Lankester’s Transl.) It would be a difficult matter, indeed, to cram more blunders into one short sentence! We will not, and need not, undertake to defend the supernatural here. Suffice it to say, that the initiation of life in inorganic matter by the Author of Life would not be a creation, nor a miracle, nor a phenomenon pertaining to the supernatural order.

The principle of the minimum forbids us to postulate the superfluous, and a creative act would be superfluous in the production of the first organisms. Inorganic nature contains all the material elements found in living organisms, and all organisms, in fact, derive their matter from the inorganic world. If, therefore, they are thus dependent in their continuance upon a supply of matter administered by the inorganic world, it is to be presumed that they were likewise dependent on that source of matter in their first origin. In other words, the material substrata of the first organisms were not produced anew, but derived from the elements of the inorganic world. Hence they were not created, but formed out of preëxistent matter. A creative act would involve total production, and exclude the preëxistence of the constituent material under a different form. A formative act, on the contrary, is a partial production, which presupposes the material out of which a given thing is to be made. Hence the Divine act, whereby organic life was first educed from the passive potentiality of inorganic matter, was formative and not creative. Elements preëxistent in the inorganic world were combined and intrinsically modified by impressing upon them a new specification, which raised them in the entitive and dynamic scale, and integrated them into units capable of self-regulation and reflexive action. This modification, however, was intrinsic to the matter involved and nothing was injected into matter from without. Obviously, therefore, the production of the first organisms was not a creation, but a formation.

Still less was it a miracle; for a miracle is a visible interposition in the course of nature by a power superior to the powers of nature. A given effect, therefore, is termed miraculous with express reference to some existing natural agency, whose efficacy it, in some way, exceeds. If there existed in inorganic nature some natural process of self-vivification, then any Divine interposition to produce life independently of this natural agency, would be a miraculous intervention. As a matter of fact, however, inorganic nature is destitute of this power of self-vitalization, and consequently no natural agency was superseded or overridden by the initial imparting of life to lifeless matter. Life was not ordained to originate in any other way. Given, therefore, this impotence of inorganic nature, it follows that an initial vivification of matter by Divine power was demanded by the very nature of things. The Divine action did not come into competition, as it were, with existing natural agencies, but was put forth in response to the exigencies of nature itself. It cannot, therefore, be regarded as miraculous.

Nor, finally, is there any warrant for regarding such an initial vivification of matter as supernatural. Only that is supernatural which transcends the nature, powers, and exigencies of all things created or creatable. But, as we have seen, if life was to exist at all, a primal animation of inanimate matter by Divine power was demanded by the very nature of things. Here the Divine action put forth in response to an exigency of nature and terminated in the constitution of living nature itself. Now, the effect of a Divine action, by which the natures of things are initially constituted, plainly pertains to the order of nature, and has nothing to do with the supernatural. Hence the primordial constitution by Divine power of living nature was not a supernatural, but a purely natural, event.