Part 6

Phil.--If the awful chasms of dark masses of rock surrounding us appear like the work of demons who might be imagined to have risen from the centre of the earth, the beautiful works of Nature above our heads may be compared to a scenic representation of a temple or banquet hall for fairies or genii, such as those fabled in the Arabian romances.

The Unknown.--A poet might certainly place here the palace of the King of the Gnomes, and might find marks of his creative power in the small lake close by on which the flame of the torch is now falling, for there it is that I expect to find the extraordinary animals which have been so long the objects of my attention.

Eub.--I see three or four creatures, like slender fish, moving on the mud below the water.

The Unknown.--I see them; they are the Protei. Now I have them in my fishing-net, and now they are safe in the pitcher of water. At first view you might suppose this animal to be a lizard, but it has the motions of a fish. Its head and the lower part of its body and its tail bear a strong resemblance to those of the eel; but it has no fins, and its curious bronchial organs are not like the gills of fishes: they form a singular vascular structure, as you see, almost like a crest, round the throat, which may be removed without occasioning the death of the animal, which is likewise furnished with lungs. With this double apparatus for supplying air to the blood, it can live either below or above the surface of the water. Its fore-feet resemble hands, but they have only three claws or fingers, and are too feeble to be of use in grasping or supporting the weight of the animal; the hinder feet have only two claws or toes, and in the larger specimens are found so imperfect as to be almost obliterated. It has small points in place of eyes, as if to preserve the analogy of Nature. It is of a fleshy whiteness and transparency in its natural state; but when exposed to light, its skin gradually becomes darker, and at last gains an olive tint. Its nasal organs appear large, and it is abundantly furnished with teeth: from which it may be concluded that it is an animal of prey; yet in its confined state it has never been known to eat, and it has been kept alive for many years by occasionally changing the water in which it was placed.

Eub.--Is this the only place in Carniola where these animals are found?

The Unknown.--They were first discovered here by the late Baron Zois; but they have since been found, though rarely, at Sittich, about thirty miles distant, thrown up by water from a subterraneous cavity; and I have lately heard it reported that some individuals of the same species have been recognised in the calcareous strata in Sicily.

Eub.--This lake in which we have seen these animals is a very small one. Do you suppose they are bred here?

The Unknown.--Certainly not. In dry seasons they are seldom found here, but after great rains they are often abundant. I think it cannot be doubted that their natural residence is in an extensile deep subterranean lake, from which in great floods they sometimes are forced through the crevices of the rocks into this place where they are found; and it does not appear to me impossible, when the peculiar nature of the country in which we are is considered, that the same great cavity may furnish the individuals which have been found at Adelsberg and at Sittich.

Eub.--This is a very extraordinary view of the subject. Is it not possible that it may be the larva of some large unknown animal inhabiting these limestone cavities? Its feet are not in harmony with the rest of its organisation; and were they removed, it would have all the characters of a fish.

The Unknown.--I cannot suppose that they are larvae. There is, I believe, in Nature no instance of a transition by this species of metamorphosis from a more perfect to a less perfect animal. The tadpole has a resemblance to a fish before it becomes a frog; the caterpillar and the maggot gain not only more perfect powers of motion on the earth in their new state, but acquire organs by which they inhabit a new element. This animal, I dare say, is much larger than we now see it when mature in its native place; but its comparative anatomy is exceedingly hostile to the idea that it is an animal in a state of transition. It has been found of various sizes, from that of the thickness of a quill to that of the thumb, but its form of organs has been always the same. It is surely a perfect animal of a peculiar species. And it adds one instance more to the number already known of the wonderful manner in which life is produced and perpetuated in every part of our globe, even in places which seem the least suited to organised existences. And the same infinite power and wisdom which has fitted the camel and the ostrich for the deserts of Africa, the swallow that secretes its own nest for the caves of Java, the whale for the Polar seas, and the morse and white bear for the Arctic ice, has given the proteus to the deep and dark subterraneous lakes of Illyria--an animal to whom the presence of light is not essential, and who can live indifferently in air and in water, on the surface of the rock, or in the depths of the mud.

Phil.--It is now ten years since I first visited this spot. I was exceedingly anxious to see the proteus, and came here with the guide in the evening of the day I arrived at Adelsberg; but though we examined the bottom of the cave with the greatest care, we could find no specimens. We returned the next morning and were more fortunate, for we discovered five close to the bank on the mud covering the bottom of the lake; the mud was smooth and perfectly undisturbed, and the water quite clear. This fact of their appearance during the night seemed to me so extraordinary, that I could hardly avoid the fancy that they were new creations. I saw no cavities through which they could have entered, and the undisturbed state of the lake seemed to give weight to my notion. My reveries became discursive; I was carried in imagination back to the primitive state of the globe, when the great animals of the sauri kind were created under the pressure of a heavy atmosphere; and my notion on this subject was not destroyed when I heard from a celebrated anatomist, to whom I sent the specimens I had collected, that the organisation of the spine of the proteus was analogous to that of one of the sauri, the remains of which are found in the older secondary strata. It was said at this time that no organs of reproduction had been discovered in any of the specimens examined by physiologists, and this lent a weight to my opinion of the possibility of their being actually new creations, which I suppose you will condemn as wholly visionary and unphilosophical.

Eub.--From the tone in which you make your statements, I think you yourself consider them as unworthy of discussion. On such ground eels might be considered new creations, for their mature ovaria have not yet been discovered, and they come from the sea into rivers under circumstances when it is difficult to trace their course.

The Unknown.--The problem of the reproduction of the proteus, like that of the common eel, is not yet solved; but ovaria have been discovered in animals of both species, and in this instance, as in all others belonging to the existing order of things, Harvey's maxim of "omne vivum ab ovo" will apply.

Eub.--You just now said that this animal has been long an object of attention to you; have you studied it as a comparative anatomist, in search of the solution of the problem of its reproduction?

The Unknown.--No; this inquiry has been pursued by much abler investigators: by Schreiber and Configliachi; my researches were made upon its respiration and the changes occasioned in water by its bronchia.

Eub.--I hope they have been satisfactory.

The Unknown.--They proved to me, at least, that not merely the oxygen dissolved in water, but likewise a part of the azote, was absorbed in the respiration of this animal.

Eub.--So that your researches confirm those of the French savants and Alexander von Humboldt, that in the respiration of animals which separate air from water, both principles of the atmosphere are absorbed.

Phil.--I have heard so many and such various opinions on the nature of the function of respiration during my education and since, that I should like to know what is the modern doctrine on this subject. I can hardly refer to better authority than yourself, and I have an additional reason for wishing for some accurate knowledge on this matter, having, as you well know, been the subject of an experiment in relation to it which, but for your kind and active assistance, must have terminated fatally.

The Unknown.--I shall gladly state what I know, which is very little. In physics and in chemistry, the science of dead matter, we possess many facts and a few principles or laws; but whenever the functions of life are considered, though the facts are numerous, yet there is, as yet, scarcely any approach to general laws, and we must usually end where we begin by confessing our entire ignorance.

Eub.--I will not allow this ignorance to be entire. Something, undoubtedly, has been gained by the knowledge of the circulation of the blood and its aeration in the lungs--these, if not laws, are at least fundamental principles.

The Unknown.--I speak only of the functions in their connection with life. We are still ignorant of the source of animal heat, though half a century ago the chemists thought they had proved it was owing to a sort of combustion of the carbon of the blood.

Phil.--As we return to our inn I hope you will both be so good as give me your views of the nature of this function, so important to all living things; tell me what you know, or what you believe, or what others imagine they know.

The Unknown.--The powers of the organic system depend upon a continued state of change. The waste of the body produced in muscular action, perspiration, and various secretions, is made up for by the constant supply of nutritive matter to the blood by the absorbents, and by the action of the heart the blood is preserved in perpetual motion through every part of the body. In the lungs, or bronchia, the venous blood is exposed to the influence of air and undergoes a remarkable change, being converted into arterial blood. The obvious chemical alteration of the air is sufficiently simple in this process: a certain quantity of carbon only is added to it, and it receives an addition of heat or vapour; the volumes of elastic fluid inspired and expired (making allowance for change of temperature) are the same, and if ponderable agents only were to be regarded it would appear as if the only use of respiration were to free the blood from a certain quantity of carbonaceous matter. But it is probable that this is only a secondary object, and that the change produced by respiration upon the blood is of a much more important kind. Oxygen, in its elastic state, has properties which are very characteristic: it gives out light by compression, which is not certainly known to be the case with any other elastic fluid except those with which oxygen has entered without undergoing combustion; and from the fire it produces in certain processes, and from the manner in which it is separated by positive electricity in the gaseous state from its combinations, it is not easy to avoid the supposition that it contains, besides its ponderable elements, some very subtle matter which is capable of assuming the form of heat and light. My idea is that the common air inspired enters into the venous blood entire, in a state of dissolution, carrying with it its subtle or ethereal part, which in ordinary cases of chemical change is given off; that it expels from the blood carbonic acid gas and azote; and that in the course of the circulation its ethereal part and its ponderable part undergo changes which belong to laws that cannot be considered as chemical--the ethereal part probably producing animal heat and other effects, and the ponderable part contributing to form carbonic acid and other products. The arterial blood is necessary to all the functions of life, and it is no less connected with the irritability of the muscles and the sensibility of the nerves than with the performance of all the secretions.

Eub.--No one can be more convinced than I am of the very limited extent of our knowledge in chemical physiology, and when I say that, having been a disciple and friend of Dr. Black, I am still disposed to prefer his ancient view to your new one, I wish merely to induce you to pause and to hear my reasons; they may appear insufficient to you, but I am anxious to explain them. First, then, in all known chemical changes in which oxygen gas is absorbed and carbonic acid gas formed, heat is produced. I could mention a thousand instances, from the combustion of wood or spirits of wine to the fermentation of fruit or the putrefaction of animal matter. This general fact, which may be almost called a law, is in favour of the view of Dr. Black. Another circumstance in favour of it is, that those animals which possess the highest temperature consume the greatest quantity of air, and, under different circumstances of action and repose, the heat is in great measure proportional to the quantity of oxygen consumed. Then those animals which absorb the smallest quantity of air are cold-blooded. Another argument in favour of Dr. Black's opinion is the change of colour of blood from black to red, which seems to show that it loses carbon.

The Unknown.--With the highest respect for the memory of Dr. Black, and for the opinion of his disciple, I shall answer the arguments I have just heard. I will not allow any facts or laws from the action of dead matter to apply to living structures; the blood is a living fluid, and of this we are sure that it does not burn in respiration. The terms warmth and cold, as applied to the blood of animals, are improper in the sense in which they have been just used; all animals are, in fact, warm-blooded, and the degrees of their temperature are fitted to the circumstances under which they live, and those animals, the life of which is most active, possess most heat, which may be the result of general actions, and not a particular effect of respiration. Besides, a distinguished physiologist has rendered it probable that the animal heat depends more upon the functions of the nerves than upon any result of respiration. The argument derived from change of colour is perfectly delusive; it would not follow if carbon were liberated from the blood that it must necessarily become brighter; sulphur combining with charcoal becomes a clear fluid, and a black oxide of copper becomes red in uniting with a substance which abounds in carbon. No change in sensible qualities can ever indicate with precision the nature of chemical change. I shall resume my view, which I cannot be said to have fully developed. When I stated that carbonic acid was formed in the venous blood in the processes of life, I meant merely to say that this blood, in consequence of certain changes, became capable of giving off carbon and oxygen in union with each other, for the moment inorganic matter enters into the composition of living organs it obeys new laws. The action of the gastric juice is chemical, and it will only dissolve dead matters, and it dissolves them when they are in tubes of metal as well as in the stomach, but it has no action upon living matter. Respiration is no more a chemical process than the absorption of chyle; and the changes that take place in the lungs, though they appear so simple, may be very complicated; it is as little philosophical to consider them as a mere combustion of carbon as to consider the formation of muscle from the arterial blood as crystallisation. There can be no doubt that all the powers and agencies of matter are employed in the purposes of organisation, but the phenomena of organisation can no more be referred to chemistry than those of chemistry to mechanics. As oxygen stands in that electrical relation to the other elements of animal matter which has been called electropositive, it may be supposed that some electrical function is exercised by oxygen in the blood; but this is a mere hypothesis. An attempt has been made founded on experiments on the decomposition of bodies by electricity to explain secretion by weak electrical powers, and to suppose the glands electrical organs, and even to imagine the action of the nerves dependent upon electricity; these, like all other notions of the same kind, appear to me very little refined. If electrical effects be the exhibition of certain powers belonging to matter, which is a fair supposition, then no change can take place without their being more or less concerned; but to imagine the presence of electricity to solve phenomena the cause of which is unknown is merely to substitute one undefined word for another. In some animals electrical organs are found, but then they furnish the artillery of the animal and means of seizing its prey and of its defence. And speculations of this kind must be ranked with those belonging to some of the more superficial followers of the Newtonian philosophy, who explained the properties of animated nature by mechanical powers, and muscular action by the expansion and contraction of elastic bladders; man, in this state of vague philosophical inquiry, was supposed a species of hydraulic machine. And when the pneumatic chemistry was invented, organic structures were soon imagined to be laboratories in which combinations and decompositions produced all the effects of living actions; then muscular contractions were supposed to depend upon explosions like those of the detonating compounds, and the formation of blood from chyle was considered as a pure chemical solution. And, now that the progress of science has opened new and extraordinary views in electricity, these views are not unnaturally applied by speculative reasoners to solve some of the mysterious and recondite phenomena of organised beings. But the analogy is too remote and incorrect; the sources of life cannot be grasped by such machinery; to look for them in the powers of electro-chemistry is seeking the living among the dead: that which touches will not be felt, that which sees will not be visible, that which commands sensations will not be their subject.

Phil.--I conclude, from what you last said, that though you are inclined to believe that some unknown subtle matter is added to the organised system by respiration, yet you would not have us believe that this is electricity, or that there is any reason to suppose that electricity has a peculiar and special share in producing the functions of life.

The Unknown.--I wish to guard you against the adoption of any hypothesis on this recondite and abstruse subject. But however difficult it may be to define the exact nature of respiration, yet the effect of it and its connexions with the functions of the body are sufficiently striking. By the action of air on the blood it is fitted for the purposes of life, and from the moment that animation is marked by sensation or volition, this function is performed, the punctum saliens in the ovum seems to receive as it were the breath of life in the influence of air. In the economy of the reproduction of the species of animals, one of the most important circumstances is the aeration of the ovum, and when this is not performed, from the blood of the mother as in the mammalia by the placenta, there is a system for aerating as in the oviparous reptiles or fishes, which enables the air freely to pass through the receptacles in which the eggs are deposited, or the egg itself is aerated out of the body through its coats or shell, and when air is excluded, incubation or artificial heat has no effect. Fishes which deposit their eggs in water that contains only a limited portion of air, make combinations which would seem almost the result of scientific knowledge or reason, though depending upon a more unerring principle, their instinct for preserving their offspring. Those fishes that spawn in spring or the beginning of summer and winch inhabit deep and still waters, as the carp, bream, pike, tench, &c., deposit their eggs upon aquatic vegetables, which by the influence of the solar light constantly preserve the water in a state of aeration. The trout, salmon, hucho, and others of the Salmo genus, which spawn in the beginning or end of winter, and which inhabit rivers fed by cold and rapid streams which descend from the mountains, deposit their eggs in shallows on heaps of gravel, as near as possible to the source of the stream where the water is fully combined with air; and to accomplish this purpose they travel for hundreds of miles against the current, and leap over cataracts and dams: thus the Salmo salar ascends by the Rhone and the Aar to the glaciers of Switzerland, the hucho by the Danube, the Isar, and the Save, passing through the lakes of the Tyrol and Styria to the highest torrents of the Noric and Julian Alps.