Part 3

If the whole remaining line of idioplasmic determinants in an ontogeny has reached development, the development of the germ-forming determinants finally follows as well from the configuration of the idioplasm as from the nature of the organism. The individual is capable of reproduction and the new ontogenies begin in the reproductive cells.

10. TRANSMISSION OF IDIOPLASMIC DETERMINANTS IN LOCAL VARIATION AND IN FECUNDATION.

The automatic progressive or perfecting transformation of the idioplasm is probably active in all stages of development, and proceeds regularly in all parts of the organism, because the idioplasm preserves its configuration at all times and places during the ontogeny. External stimuli impign upon the organism usually at a definite point, but they not only effect a local transformation of the idioplasm but also reproduce themselves in a dynamic manner in the entire idioplasm, which is in unbroken connection throughout the whole individual. The idioplasm is thus changed everywhere in the same manner, so that the germ cells that are given off at any point feel and inherit the effects of those local stimuli.

In the formation of the germ cells in sexual reproduction, the idioplasms of both parents must come into contact with each other, whereupon there results either a material union and formation of a mixed idioplasm or perhaps rather a dynamic action; and through these agencies there is produced a remodeled form which is, however, exactly equivalent to the combined idioplasms entering into it. Fertilization by diosmose of the spermatic substance is impossible.

This assertion is a direct corollary from the structure of the determinants and the idioplasm. If the idioplasm of the fertilizing cell were to pass through the membrane about the ovum by osmosis, its organized structure would be lost.--Trans.

In the idioplasm of a germ cell arising from the crossing of unlike individuals the micellar rows of the individual determinants have sometimes an intermediate constitution and produce characteristics in the organism which are intermediate between the characteristics of the parents. Sometimes the micellar rows derived from the father and mother respectively lie side by side unchanged in the idioplasm of the offspring in distinct groupings and may reproduce in the organism their respective characteristics side by side, or only one of them may develop, while the other remains latent.

On account of the union of both idioplasms as the result of fecundation, two sexually mature organisms are the more able to form with each other a viable germ cell, the nearer they are genetically related--that is, the more nearly the male and female idioplasms correspond in their configuration and chemical nature, because in this case the micellar arrangements are best suited to each other, and the idioplasm of the new fertile germ cell receives its most suitable nourishment from the mother. If, however, self-fecundation or the closest in-and-in breeding often yields products of less virility and is avoided by nature, this is the result of injurious influences which make themselves felt later on. This is because incompatibilities may be present in too closely related idioplasms and these are sources of weakness in unrestricted development. The more complicated is the idioplasm, the oftener this occurs, whereas absolute lack of crossing is not detrimental to the simplest (asexual) organisms.

11. ACTION OF EXTERNAL INFLUENCES.

The environment provides the organism above all with force and matter for its life processes. It causes no permanent variation and has only an ontogenetic significance, if the limits of the idioplasmic elasticity are not exceeded; it maintains the growth and metabolic assimilation of the individual, and conditions individual (not hereditary) differences, which constitute "nutrition varieties." (See page 30.) These appear as the direct results of operating causes.

In order to explain adaptations Naegeli assumes that external influences, if acting at the same point in a given manner for a long time, may induce slight adaptive variations which are perpetuated and increased. On the important subject of adaptation in general Naegeli is almost diametrically opposed to Darwin and Weismann. Naegeli assigns to the principle of utility a very limited sphere; Weismann regards adaptation as all-powerful. According to Naegeli, the organic world would have become much what it is, if natural selection and adaptation had performed no part in the operations of nature. He aptly says, that natural selection prunes the phylogenetic tree, but does not cause new branches to grow. He allows that the principle of selection is well suited to explain the adaptation of organisms to their environment and the suitableness and physiological peculiarities of their structure, but he asserts that in the definiteness of variation of plants and in their progressive differentiation there is evidence of a higher and controlling perfecting principle.--Trans.

When the stress of environment exceeds the limits of idioplasmic elasticity, its influence brings about permanent variations, which are imperceptibly small, it is true, in the single individual, but which, when the stimulus is active for a long period of time in the same manner, increase to perceptible magnitude. These variations are inheritable in the phylogenetic sense and contribute to the formation of varieties and species; they always appear as the results of more or less secondary reactions which make their appearance with stimuli exerted by external causes.

External stimuli exerted on the organism are reproduced in the idioplasm. Since the stimulus is discontinued with each change of the ontogeny and only the idioplasm persists, permanent variations are produced only in the idioplasm by those conditions that produce visible transformations in the mature organism.

The phylogenetic action of external stimuli gives the definite character of adaptation to the idioplasm as it becomes more complex from inner causes and probably these external stimuli have the power to alter this impress only as new idioplasm is automatically formed.

If an external cause acts continuously upon a phylogenetic line, the corresponding variation of the idioplasm reaches, after a time, a maximum, and thus comes to an end, either because the nature of the substance permits no new rearrangement or because the stimulus is no longer active. The cessation of the stimulus results from a micellar rearrangement which indicates the character of the adaptation. If the action of the stimulus lasts for only a short time, the incipient rearrangement of the idioplasm stops, or proceeds independently on account of the impulse received, and the determinant becomes capable of development, even after the impulse has long ceased to act.

Since various intervening transpositions follow upon a stimulus in the organism, the final result which appears as a reaction may turn out variously. The same external causes may, according to the nature of the organism and other circumstances, have very unlike variations as a result. But the internal rearrangement produces in a definite case very definite variations.

On account of the various intermediate steps it is often difficult to discover the external cause of a given adaptive variation. In many cases we recognize it without difficulty in a definite mechanical process or in warmth, light or evaporation. For the most part the stimulus awakens in the organism merely a want, which the reaction of the organism endeavors to supply. Hence it appears that want or lack alone is able to bring about such reactions. Moreover, in the sphere of sex, electric(?) attractions and repulsions co-operate between the idioplasmic determinants to produce phylogenetic variations.

The adaptations of the fully developed organism, which are the results of external influences, consist either only of a specific molecular character (irritability), by virtue of which the individual is capable of responding to those influences with temporary or permanent phenomena, or they consist of finished arrangements. The latter have, in general, a double function: either they protect the organism from external influences whose results they are, or they place it in a condition to apply such environmental influences to their advantage. The preponderance of the one or the other led to the development of the plant or the animal kingdom. In the one case the primordial plasma formed in the cellulose cell wall a stimulus-proof covering. On account of this cell membrane being insensible to stimuli, adaptations in the plant kingdom were restricted essentially to the spheres of nutrition and reproduction. In the other case the irritability and mobility of the primordial plasma increased so that it was placed in a condition to avoid the irritant or make it serviceable by accommodating itself to it. The cells sensible to irritants led in the animal kingdom to the formation of organs of sense and the nervous system.

12. CONDITIONS OF PHYLOGENETIC DEVELOPMENT OF THE DETERMINANTS. ATAVISM.

In the primordial condition, formation and development of the determinants coincide, since the plasma constituting the organism possesses the capability of growing by intussusception of new micellae and of changing this growth through the action of inner and outer causes. But as the primordial plasma differentiates into idioplasm and soma-plasm, the formation of determinants consists in the transformation of the idioplasm, while the development of determinants consists in the production of soma-plasm and of non-plasmic substances under the influence of the idioplasm.

Only the mature determinant is able to develop, especially if, at the same time, a related and heretofore active determinant must be forced back into the latent condition. But the determinant of an absolutely new form of adaptation, which does not take the place of a preceding one, must develop enough before it can become outwardly manifest, for it to be possessed of a sufficient amount of molecular energy to render its activity possible. For this reason the characteristics of the developed organism change abruptly, notwithstanding the fact that the transformation of the idioplasm has proceeded very gradually.

The configuration of the idioplasm becomes continually more complex through the automatic action of the perfecting process, and by this means the organism ascends to higher stages of organization. Hence the viable determinants of organization or perfection are always overtaken after a certain time by that movement and forced into the latent condition. They then become continually weaker, and are at last completely destroyed. Only in the first period after their becoming latent can such determinants pass again into a developmental condition and thus allow the organism to revert to the next preceding stage of organization.

Since the configuration of the idioplasm, which becomes more complex from internal causes, always assumes a definite character of adaptation in consequence of the action of external causes, the adaptation determinants capable of development may become more and more weakened and at last latent when other external causes produce other adaptation determinants. But these determinants may be revived by the renewed activity of the former causes, and thus rendered capable of development. Hence the organism may show the most various reversions with respect to its adaptations. But in such reversions the earlier forms never quite return, because in the meanwhile the idioplasm has changed somewhat in consequence of its automatic progress, and therefore lends to the adaptations which assume the earlier character a somewhat different expression.

13. ONTOGENETIC DEVELOPMENT OF THE DETERMINANTS.

Since the capability of the primordial plasma to grow is the original and only vital quality (Anlage), the whole ontogeny in this first stage consists in the growth of the detached parts to the adult size. In the same way the development of the determinants in all the following stages is nothing more than the growth of the substance detached as a germ cell after the manner of the changes in the character of the idioplasm in the course of phylogeny. In this manner all determinants may in the lower stages of organization reach development, but in the higher stages an increasing number of them must remain latent.

Among the viable determinants there are some that develop unconditionally during each ontogenetic period; there are also alternative determinants of which one or the other unconditionally develops; lastly, there are some that develop only under favorable circumstances. Which of two alternative determinants shall develop depends sometimes on internal, sometimes on external causes, according as the specific determinant has arisen phylogenetically through the action of internal or external causes. Climatic and nutritive influences especially affect the appearance of indefinitely developing determinants. Just so, when a determinant may develop repeatedly (as is so common in the plant kingdom) it depends especially on nutrition whether the corresponding phenomenon is repeated at intervals of greater or less length. A weakened determinant is sometimes temporarily developed by the operation of a definite stimulus.

If the integrity of the organism sustains an injury in consequence of abnormal interferences, determinants develop exceptionally at unusual points. The process is induced by accumulation of nutritive matter and by external stimuli under the force of necessity, to which the injured organism is sensible.

14. ESSENTIAL NATURE OF THE ORGANISM.

The essential nature of a thing is the sum total of its causes and effects. Organisms arise from a germ cell which consists of idioplasm and in turn they produce like germ cells. Their nature depends also on their idioplasm, i.e., on the sum total of their idioplasmic determinants. Observation of organisms, even in their fullest life history, gives us an imperfect and even false conception of their true nature. This is because observation reveals only the outer gross characters, and even these in a modification dependent upon accidental effects of nutrition, and does not reveal the finer characters founded in molecular physiology and morphology, and especially the characters latent in the idioplasm.