General Physiology: An Outline of the Science of Life

provided with extremely delicate silicious skeletons, in many tissue-cells when pressed close together into polyhedral forms, and in many spherical egg-cells ; and, in the second place, in inorganic nature the mathematically fixed body-form is wanting in all fluids. Farther, it has been maintained that inorganic bodies, such as crystals, have no organs, while the presence of these distinguishes all organisms. This also is incorrect. There exist not only organisms without proper organs, such as Amoeba and all other Rhizopoda, in which the whole liquid protoplasmic body is an organ for all things, but also inorganic structures with real organs, such as machines, in which the individual parts are provided with perfectly definite functions. Yet no one will seriously regard Amaebce as inorganic bodies, or steam-engines as living organisms.

Another difference has been sought in the claim that, in contrast to all inorganic bodies, organisms are composed of the characteristic structural elements of all living substance, cells. It is true that the cell is a specific element of the whole organic world. But that which characterises this elementary constituent, that which distinguishes it from the whole inorganic world, is not its morphological character. Objects that are composed of separate form-elements can easily be manufactured out of inorganic substances. Nature has manufactured such objects in great quantity in rocks wrhich consist of innumerable separate crystals, such as granite. That which characterises the cell is rather its chemical properties. Hence the presence of cells is not a sign of absolute structural difference.

Finally, it has been said that inorganic bodies possess a very simple uniform structure, while organisms possess a highly complex " organisation." If by "organisation" there is understood simply the more or less complex composition of organisms out of different kinds of elementary structural particles, the cells, this statement, within certain limits, is true ; although, in contrast with composite rocks, the difference is merely one of degree. But the cell must be employed for comparison, for it is in itself a complete organism. If, however, the conception of complex " organisation " be applied to the cell, it signifies merely the gross morphological variety and chemical complexity of its constituents, and such a condition can be established in a test-tube in a complex chemicophysical mixture. If by "organisation" a special kind of association of the individual constituents is understood, such as would not occur in inorganic nature, then the conception carries with it more or less mysticism, which has always been a favourite aid in explaining vital phenomena. Such a process cannot be followed in science, for science and mysticism are mutually exclusive.

Thus it is seen that a comparison of the structural relations of living and of inorganic substance does not reveal essential differences between the two. If the former be compared with a liquid rather than with a crystal, it is found that in its structural relations it differs no more from lifeless liquid mixtures than these differ among themselves, and, indeed, not so much as they differ from a crystal. A second series of differences which, it is believed, have been found between organisms and inorganic substances has reference to reproduction and derivation. These differences likewise are not fundamental, and it is easy to perceive that between the two groups no real contrast in this respect exists.

It is regarded as a characteristic sign of difference that organisms reproduce, while inorganic bodies cannot do so. This is not an absolute difference, for many organisms are known that live and yet can never reproduce.- Thus, it is well known that the power of reproduction is wanting throughout life in the so-called workers, those individuals in communities of ants and bees which form the great majority of the community and in which the sexual organs are undeveloped ; notwithstanding this latter fact they must be regarded as living organisms. Further, reproduction in organisms consists simply in a giving-off of a certain portion of the body-substance, a division of the individual body. This fact shows most distinctly, i.e., is less masked by accompanying accessory phenomena, in unicellular organisms. An Amoeba, for example, constricts itself into halves, and each half continues to live as a new Amoeba. But if reproduction in its essentials consists merely in the division of substance, no fundamental difference exists between the process in a living cell and that in an inorganic body. A drop of mercury that falls upon the floor is divided, into a number of small globules, all of which are drops of mercury.

It has been said, further, that organisms are always derived from other organisms, while inorganic bodies can be derived from both organisms and inorganic bodies. Thus, it is impossible to manufacture even the simplest organism artificially from inorganic substances, while it is not difficult to obtain inorganic bodies — e.g., water — in a variety of ways from both organic and inorganic substances. This appears to be an absolute difference, for it is true that in spite of all endeavours no one has succeeded in demonstrating that organisms can be formed from inorganic matters either in nature or in the laboratory. Nevertheless, this difference cannot be regarded as really absolute, for it can be replied that organic substance is constantly being built out of inorganic substance in the plant-body, this being the exclusive method of construction in plants. To this it has been rejoined in

turn that this origin of organic out of inorganic substance is possible only with the help of living organisms ; Preyer ('80) has said that organisms are distinguished from inorganic bodies by the fact that they always presuppose the existence of living substance. Only in this form does the distinction hold good, at most, for the present time. Virchow's dictum, " Omnis celhda e ccllula" which is the generalisation that has become necessary in the course of time from the old dictum of Harvey, " Omne vivum ex ovo" holds good only for the conditions that now prevail upon the earth's surface. If we go backward in the development of the earth, we soon come to a time when the earth was an incandescent mass, upon which no cell could exist. Cells must, therefore, have arisen at some time from masses of matter that were not cells. At this point the following alternative is presented : Either, as the theory of spontaneous generation assumes, organisms have arisen at some time out of inorganic substances, or, as the theory of the continuity of life demands, the conception of life must be applied also to those bodies from which cells have developed, although they were totally different from the living substance of present organisms. If the former be accepted, the difference in the derivation of the two groups of bodies disappears of itself, for then not only inorganic, but also organic nature is derived from nonliving substance. Preyer decides upon the second assumption ; he considers as living the mass of matter out of which cells have developed, and even the whole incandescent mass of the earth itself; and he extends still further Harvey's dictum to " Omne vivum e vivo" thereby expressing the idea that life has never originated, but has existed from eternity.

But the difficulty of establishing a fundamental difference between organisms and inorganic bodies upon the ground of their derivation is not thus set aside. For, in harmony with his idea that the whole incandescent mass of the earth is to be considered as living, Preyer assumes that the inorganic has arisen out of the organic. Hence, not only does organic nature, but also inorganic, presuppose the existence of living substance, and it is clear that the above-mentioned difference in the derivation of the two great groups of matter disappears. It is seen, therefore, that even by such an extension of the conception of life as Preyer's the difference in derivation cannot be maintained for the earlier period of the earth's development.

Just as little absolute difference exists between the organism and the inorganic body in their development as in their reproduction and derivation from like bodies. By development is understood a series of changes undergone by the new-born organism, which make it finally like its parents. Such changes occur in inorganic nature likewise, and are there not fundamentally different from those in organisms. E.g., if a piece of sulphur be melted in a vessel and the melted mass be poured into water, there is obtained a tough, brown, gummy substance which has not the least external resemblance to the piece of sulphur from which it came. But if it be left for a day or two, it becomes gradually harder and more solid, its brown colour fades and changes to a yellowish, and after some time the whole mass takes on again the appearance of common hard yellow sulphur. Here the sulphur has gone through a development which has made it again like the piece from which it was derived. But even on the part of organisms development is not an absolute sign of difference, for there are organisms that live without developing. The two equal parts into which Amoeba constricts itself are complete Amcubce, without any further process, and are distinguished by their size only from the individual from which they are derived.

Finally, an endeavour has been made, but with similar slight success, to find a distinction between organisms and inorganic substances in the manner of growth. The unfortunate contrast of the organism and the crystal, again, has led to the assertion of this difference. It has been said that the crystal grows by the apposition, the organism by the intussusception of particles ; i.e., the crystal grows by laying one particle after another upon its surface, the interior remaining fixed and unchanged, the organism, on the contrary, by taking particles into its interior and storing them between those already present. If a cell as a whole be contrasted with a crystal, this is not to be disputed ; but it has already been seen that as regards its physical characteristics the living substance of organisms in its essentials ought to be compared with a liquid. Liquids, however, grow solely by intussusception, i.e., if a soluble body be added to a liquid, e.g., salt to water, the latter dissolves the former and stores the molecules of the soluble body by diffusion between its own molecules — that is, there is here exactly the same process as in the growth of the organism.

Hence, the comparison of the genetic relations of organisms and inorganic bodies reveals no more fundamental difference between them than the consideration of their structural relations, and it is necessary to search further. A third group of differences which have been asserted to exist between organisms and inorganic bodies comprises the phenomena of movement. Movement, the most evident of all vital phenomena, was regarded in early times as a characteristic sign of life, and primitive people, in holding consistently to this idea, regarded winds and waves as living things. But the sea is no longer

called living, and, on the other hand, in the resting plant-seed there is seen a condition of the organism in which, while it is not dead, not the slightest movement can be recognised. Thus the significance of movement in its primitive form has now disappeared, and in place of it more special motile phenomena have been sought as distinguishing marks between organisms and inorganic bodies. It has been thought that a difference must be recognised in the causes that produce movements, on the one hand, of organisms, and, on the other, of inorganic bodies. The former, such as musclemovements, are said to result from internal causes — those that have their seat in the organism itself; the latter, such as the movement of waves and clouds, from external causes — those that, like the wind, act upon the object from without. The mystical vital force is here more or less evident. But we have already become convinced of the non-existence of such a force, and the claim of such a difference in the causes of movement cannot be maintained. Moreover, in many cases it is difficult to draw a sharp boundary between internal and external causes. E.g., if a steam-engine, and not winds and waves, be considered, it can be said of it, with as much right as of the organism, that it works from internal causes, for the pressure of the steam which drives the piston and puts the wheels in motion is in the interior of the boiler.

But it has been said that the difference between the causes of motion in the steam-engine and those in the organism lies in the fact that the former cannot work unless it is heated from the outside, while the latter works of itself. This is wholly untrue. The organism also must be heated if it is to continue in activity, i.e., in life, exactly as the steam-engine. Its heating is by the introduction of food. The analogy between the heating of the steam-engine and the nutrition of the organism goes very far. The carbon-containing food is burned in the organism in great part as is the coal in the steam-engine — i.e., the food-stuffs are oxidised by the oxygen taken in in respiration, as the coal is oxidised — and in both cases there is obtained as the end-product carbonic acid. If the introduction of food be interrupted, the activity of the organism ceases after a time when all the ingested food is consumed, similarly as with the steam-engine ; in both, movement is stopped.

The comparison of the organism with the steam-engine allows the untenableness of the claim of another difference, closely associated with the previous one, to be at once recognised. It has been said, namely, that organisms are in dynamical equilibrium— i.e., the same quantity of energy that is introduced into the organism leaves it again in some form — while inorganic bodies are in stable equilibrium. It is true that organisms in the adult state are in dynamical equilibrium. But, when this is put forward as a real difference in comparison with

inorganic bodies, the crystal alone is again in mind. The steamengine, however, is an inorganic system in which dynamic equilibrium exists very clearly; for by the mediation of heat the system gives off to the outside as mechanical energy exactly as much energy as is introduced by the burning of the coal. Finally, irritability has been brought forward as a general characteristic of organisms in contrast to inorganic bodies. In reviewing the history of physiological investigation it was seen that at first very indefinite ideas were associated with the word " irritability," and, in order to guard against misunderstandings, the conception must be definitely formulated. It can be said in general that irritability is the capacity of a body to react to an external influence by some kind of change in its condition, in which the extent of the reaction stands in no definite proportion to the extent of the influence. As a matter of fact, irritability, or excitability, is a property of all living substance, whether the organism responds to the external influence by the production of definite substances, as with secreting gland-cells, or definite forms of energy, as with muscle-cells, phosphorescent cells, and electric cells, or whether it responds by depression or even standstill of its vital activities. But irritability is not the exclusive property of organisms, for lifeless substances are likewise irritable and respond to external influences by definite changes, e.g., by the production of definite substances or of energy, in which process the extent of the production by no means corresponds always to the extent of the external impulse. The clearest examples of such cases are afforded by explosive substances. By a slight shock nitroglycerine is decomposed into water, carbonic acid, oxygen and nitrogen, the process being accompanied by a powerful evolution of energy; in other words, nitroglycerine responds to an external influence by an enormous production of energy and a change of material.

Hence irritability is not an absolute sign of difference between organisms and inorganic bodies, and it is seen that a fundamental contrast between the two is afforded no more by their dynamical than by their structural and genetic relations. We will, therefore, search still further. It is by a comparison of their chemical relations that a difference is finally found to exist between organisms and inorganic bodies. It has been seen that a specific vital element exists in the organism no more than a specific vital force. The chemical elements that compose the organism occur without exception in inorganic nature also. Therefore, a fundamental chemical contrast between organic and inorganic substance is not to be

expected, i.e., a contrast that rests upon a difference as regards chemical elements. But a difference does exist in the kind of combinations into which the elements enter. It was seen above that chemical compounds are present in living substance, that never occur in the inorganic world; such are proteids, carbohydrates and fats. Of most importance is the fact that one group of these chemical bodies, the proteids, belong to all organisms without exception. Just as there is no single organism, whether living or dead, in which proteids are wanting, so there are no inorganic bodies in nature in which even an approximately similar substance is present. The possession of the highly complex proteid molecule is, therefore, a definite mark of distinction of the organism in its relation to all inorganic bodies.

But some have gone still further and have endeavoured to find an absolute difference between the two bodies, not only in the existence of certain compounds, but also in the order of the chemical processes in the active organism. It is said that living substance is characterised by its metabolism, in which definite compounds are formed continually, are broken down, give off* their decomposition-products to the outside, and are reformed at the expense of the substances taken in from the outside as food ; hence a continual streaming of matter through the living substance takes place, being conditioned by the construction and destruction of the compounds in question. Metabolism is, indeed, a characteristic process of the living organism, and it will be seen later that upon it the vital process rests; but it is solely a process that distinguishes the living organism from the dead organism and not from inorganic substance, for it is not confined to organisms, but occurs also among inorganic bodies. A simple example of this is found in the behaviour of nitric acid in the production of concentrated sulphuric acid. If nitric acid be mixed with sulphurous anhydride, which is obtained in the manufacture of sulphuric acid by roasting sulphur ore, the sulphurous acid withdraws oxygen from the nitric acid and passes over into sulphuric acid, while the nitric acid becomes nitrous acid. If the constant entrance of fresh air and water be provided, the nitric acid is constantly reformed from the nitrous acid and gives a part of its oxygen again to new quantities of sulphurous acid, so that the molecule of nitric acid is continually being alternately broken down with loss of oxygen and built up with absorption of oxygen. In this manner with the same quantity of nitric acid an unlimited quantity of sulphurous acid can be changed into sulphuric acid.

Thus here in a simple form, i.e., in a simple chemical compound, is a regular metabolism, a succession of destructions and constructions of a substance along with the gain and loss of substances, which corresponds in principle, even to its details, to the metabolism of organisms ; nevertheless, nitric acid is an inorganic compound, Such phenomena are relatively rare and occur in free nature, where their conditions are not artificially established by human agency, only very seldom. Nevertheless, they do not permit the presence of a metabolism to be maintained as an absolute difference between living organisms and inorganic bodies.

Thus the fact has been established that a fundamental contrast between living organisms and inorganic bodies does not exist. In contradistinction to all inorganic nature, however, organisms are characterised solely by the possession of certain highly complex chemical compounds, especially proteids. In India, where mystery and magic have always prevailed, the belief seems to have existed for a long time, that many men, especially the so-called fakirs, whose existences are full of privation and self-inflicted torture, and who are supposed to possess special holiness, have the remarkable power of voluntarily putting a complete stop to their lives for a time and later resuming them undisturbed and unchanged. A great number of such cases, in which the fakirs have been buried in this condition of suspended animation and after some time have been taken from their graves, have been reported by travellers from India. James Braid ('50), the wellknown discoverer of hypnotism, has collected some of the most authentic cases, and supported them by the testimony of witnesses. One of these cases, which may serve as a type, is the following :

At the palace of Runjeet Singh, in a square building which had in the middle a closed room, a fakir, who had voluntarily put himself into a lifeless condition, had been sewed up in a sack and walled in, the single door of the room having been sealed with the private seal of Runjeet Singh. (To judge from the account, the air, as in all such cases, was not absolutely excluded.) In order to exclude all fraud, Runjeet Singh, who was not himself a believer in the wonderful power of the fakirs, had established a cordon of his own body-guard around the building ; in front of the latter, four sentries were stationed, who were relieved every two hours and were continually watched. Under these conditions, the fakir remained in his grave for six weeks. An Englishman, who was present during the whole event as an eye-witness, reported as follows concerning the disinterment, which took place at the end of six weeks : When the building was opened in the presence of

Run jeet Singh, the seal and all the walls were found uninjured. In the dark room of the building, which was examined with a light, the sack containing the fakir lay in a locked box, which was provided with a seal likewise uninjured. The sack, which presented a mildewed appearance, was opened, and the crouching form of the fakir was taken out. The body was perfectly stiff. A physician who was present found that nowhere on the body was a trace of a pulse-beat evident. In the meantime the servant of the fakir poured warm water over the head, laid a hot cake upon the top of the head, removed the wax with which the ears and nostrils were stopped, with a knife forcibly opened the teeth, which were tightly pressed together, drew forward the tongue which was bent backward and which repeatedly sprang back again into its position, and rubbed the closed eyelids with butter. Soon the fakir began to open his eyes, the body began to twitch convulsively, the nostrils were dilated, the skin, heretofore stiff and wrinkled, assumed gradually its normal fulness, and a few minutes later the fakir opened his lips and in a feeble voice asked Kunjeet Singh, " Do you believe me now ? "

Similar cases are reported in great number by more or less reliable witnesses. An analogous instance was observed in Europe, and is cited likewise by Braid. It is the well-known case of Colonel Townsend, of whom Dr. Cheyne, a physician of Dublin, well-known in scientific circles, narrates as follows : " He could die or expire when he pleased, and yet, by an effort or somehow, he could come to life again. He insisted so much upon us seeing the trial made that we were at last forced to comply. We all three felt his pulse first : it was distinct, though small and thready, and his heart had its usual beating. He composed himself on his back, and lay in a still posture for some time : while I held his right hand, Dr. Baynard laid his hand on his heart, and Mr. Skrine held a clear looking-glass to his mouth. I found his pulse sink gradually, till at last I could not feel any, by the most exact and nice touch. Dr. Baynard could not feel the least motion in the heart, nor Mr. Skrine perceive the least soil on the bright mirror he held to his mouth. Then, each of us, by turns, examined his arm, heart, and breath ; but could not, by the nicest scrutiny, discover the least symptom of life in him. We reasoned a long time about this odd appearance as well as we could, and finding he still continued in that condition, we began to conclude that he had, indeed, carried the experiment too far ; and at last we were satisfied that he was actually dead, and were just ready to leave him. This continued about half an hour. By nine in the morning, in autumn, as we were going away, we observed some motion about the body, and upon examination found his pulse and the motion of his heart gradually returning : he began to breathe heavily and speak softly. We were all astonished to the last

degree at this unexpected change, and after some further conversation with him, and among ourselves, went away fully satisfied as to all the particulars of this fact, but confounded and puzzled, and not able to form any rational scheme that might account for it." It is not to be denied that a priori these tales, especially those of the Indian fakirs, are calculated to awaken distrust, and a sound scepticism is the basis of all good criticism. The mistrust is increased when cases happen in which the fakirs are exposed as swindlers, as at the Hungarian Millennium Exposition in Budapest. But from the standpoint of an unprejudiced science we must say that it would be an entire mistake superciliously to regard a thing as untrue merely because at first sight the reports appear strange, and because an impostor employs it for purposes of gain. It is rather in accordance with the liberality of scientific research first carefully to test the phenomenon and to see whether genuine scientific grounds for its impossibility may be brought against it. If from all the known stories their more or less sensational accompaniments be removed, the simple statement remains that certain men can voluntarily put themselves into a state in which no vital phenomena are demonstrable by a more or less superficial examination, and can awaken later to normal life. Now, sufficient cases are known where physicians by the usual methods of their practice are able to discover absolutely no traces of vital phenomena, where pulse, respiration, movement, and irritability are not to be observed ; and yet where the person, supposably dead, has after a time returned to life. These phenomena are usually termed " apparent death," and are connected with those of normal sleep by a seriesof transition phenomena. Such transition phenomena are the continual sleep in which persons, such as the " sleeping soldier " and the " sleeping miner," continue in a state of depressed vital activity and incapable of being awakened, and, especiallv, the phenomena of the winter sleep of warm-blooded animals.

If the fact of apparent death cannot be disputed, the mysterious- and mystical in the reported tales constantly diminish and become limited solely to the power of going into such a state voluntarily. As regards this, we know that it is possible by exercise to bring under the influence of the will bodily activities, such as the movement or inhibition of certain muscles, which once took place only involuntarily. And it is known that in certain pathological conditions, especially in cases of profound hysteria, many phenomena, which are never associated with the will in normal persons, can be brought under its influence. Hence it is not justifiable to assert, a priori, the impossibility of the reported phenomena, although the reports, which come almost exclusively from the English military and civil officials, concerning fakirs that are buried alive must be received with great caution and criticism. It will be an

interesting task for the physiologists to investigate carefully these phenomena, heretofore so ill-defined, to prove by refined methods what vital phenomena are really depressed and to what degree, and finally to show how this voluntary apparent death, which, it is widely believed, has in it absolutely nothing mystical, is to be explained physiologically. How little justification there is in doubting the power of certain organisms to retain the capacity of life without exhibiting the slightest vital phenomena, and even for so long a time that the usual duration of their life is greatly surpassed, appears when we turn from the vertebrates to the invertebrates, which have been very carefully investigated in this respect.

Leeuwenhoek (1719) made the very remarkable observation that in the dust of eaves-troughs animalcules exist which are capable of drying up completely without losing the power of awakening to active life upon being moistened with rain- FIG. 41. — Macrobiotus Hufdandi, -A tardigrade, a, Creeping, in the living state. (After [R. Hertwig.) b, Dried, in the state of apparent death. water. Since their discovery by Leeuwenhoek this fact has been confirmed by a great number of observers and its details have been more fully described. It is not difficult to convince one's self of its truth. If some of the crust be scraped from an old eaves-trough or from the moss-covered side of an old tree-trunk, and the dry powder be covered with pure rain-water, often in the course of some hours a number of small animals can be seen by the aid of the microscope, actively creeping about among the particles of mud. They are mostly representatives of the wheelis

animalcules, or Rotatoria, whose bodies, extended like a telescope, have at their anterior end a locomotor organ provided with stout cilia, which on account of the apparently wheel-like motion of the cilia has been termed the wheel-organ. Besides the Rotatoria there are found chiefly the so-called bear-animalcules, or Tardigrada, clumsy mite-like animals provided with four pairs of short stumps of feet, bearing claws ; like the Rotatoria they are provided with a nervous system, digestive apparatus, etc. (Fig. 41 a). So long as this latter peculiar animal is in water, it performs all its vital phenomena like other animals. But if it be isolated and allowed to dry slowly upon a slide, it is seen that the more the water evaporates, the slower become its movements, until finally they cease entirely when the drop is dried up. Then the body gradually shrinks, the skin becomes wrinkled and folded, the form becomes gradually indistinguishable, and some time after the animal has become dried up it can scarcely be distinguished from a grain of sand (Fig. 41 fr). In this dried condition it can remain for many years without undergoing the slightest change. If it be moistened again with water, the return of life to the desiccated body after its sleep can be followed with the microscope. The awakening of the tardigrade, or the anabiosis, as Preyer ('80) has termed the process, takes place somewhat as follows: The body swells up and becomes extended, the folds and wrinkles slowly disappear, the extremities project, and the animal soon assumes its normal shape.

At first it remains quiet ; then, after a time, varying, according to the duration of the drying, from a quarter of an hour to several hours, movements, at first slow and feeble, begin and gradually become stronger and more frequent, until after some time the animal, unaided, creeps away to resume life at the point where it was interrupted. These highly remarkable phenomena of anabiosis are not limited to the Rotatoria and the Tardigrada. They have been noticed likewise in various other organisms in the course of investigations which in great number followed Leeuwenhoek's discovery. They have been observed in the so-called paste-eels, or AnguUlulidce, the small eel-like worms that live in diseased wheat-grains, in Infusoria and Amoeba, and in Bacteria,

In the same group of facts belongs also the long-known capacity of plant-seeds to remain dry for many years unchanged without losing their power of sprouting ; indeed, it has even been believed that this power can continue for an unlimited time. The statements are well known that wheat-grains found in the graves of Egyptian mummies after a rest of many thousand years have sprouted and bloomed. It has been settled, however, that these reports rest upon a delusion, for Mariette, the well-known Egyptologist, has shown that with genuine mummy wheat these experiments always fail, since all wheat-grains taken from the graves