Art. LII.—Is Life a Distinct Force?

Transactions and Proceedings of the Royal Society of New Zealand, Volume 17, 1884, Page 410

Art. LII.—Is Life a Distinct Force? By R. H. BakewellM.D., Fellow of the Royal Medical and Chirurgical Society of London, etc. [Read before the Philosophical Institute of Canterbury, 3rd July, 1884.] The question I have placed at the head of this paper is one not yet settled, although it may be admitted that there is a preponderance of opinion in favour of a negative reply. For this reason it is well worthy of discussion, and as it is one on which I have thought much and in connection with which I have made many experiments, I have selected it for discussion this evening. As this is not intended to be a metaphysical paper nor to lead to a discussion on mere abstractions, certain postulates will be requisite. Let it be granted then that matter exists as ourselves and not ourselves, that it is manifested to our senses by phenomena, that it is acted upon by certain forces or energies, and that two kinds of matter may be discerned, living and non-living. Definitions.—We define non-living matter to be that which possesses no power of motion in itself, nor of self-nutrition, nor of producing any change within itself by the action of its own parts, nor of reproduction. Living matter is an albuminoid compound, characterized by the possession of motion in itself, that is, independent of the action of any external force, by being able to assimilate food or nutriment, and by being able to reproduce its like.

With the other qualities of living matter I shall not at present deal; these three are essential to any form of living matter, and are found in all, from the humblest of the Protista up to man. Life then I should define to be,—that force or combination of forces which gives to protoplasm its power of motion, of self-nutrition, and of reproduction. In this definition it will be observed that I avoid assuming that life is a force—it may be the result of a combination of forces. Life is either somatic or molecular. In the simplest forms of living beings, the somatic and molecular life are inseparable, as the individual consists but of a single cell. If you kill an Amœba, for example, you destroy both the somatic and molecular life at the same time. But except the simplest organisms, whether vegetal or animal, living beings are built up of corpuscles, sometimes in the form of cells, sometimes in more complex tissues formed originally out of cells, each endowed with life, which is to a certain limited extent independent of the life of the whole organism. This is what is called molecular life. The life of the organism as a whole is called somatic life. It is possible in many of these organisms, particularly in what are called the higher or more complex ones, for somatic life to cease long before the individual molecules of which the being is built up have lost their vital properties. Living protoplasm, as I have before said, is an albuminoid substance. It consists of carbon, oxygen, hydrogen, and a little phosphorus and sulphur. On Motion as a quality of Living Matter.—It is admitted by every one that non-living matter, in whatever form it may be found, cannot move of itself, nor unless acted on by some external force. But living protoplasm, as long as life exists, is endowed with motion. A simple cell like the Amœba (I use the word cell for convenience—the Amœba is not properly a cell) or a leucocyte, and many of the simpler forms of vegetal and animal life can be seen to move about in the medium in which they exist. But the higher forms of vegetal life, it may be thought, do not move unless acted on by some external force. A lichen seems to cling to the rock on which it has fixed itself; and even those plants like the sensitive plant, or the sundew, or Venus' fly-trap, which are known to move and grasp objects brought into contact with them, may be thought not to move spontaneously, or without being acted upon from without. This appearance of inertia is however fallacious, for whether you examine the lichen or the forest tree that has been rooted to its native earth for a thousand years, you will find that in every part of its structure change is going on—fluids are circulating; vessels and ducts and fibres are being produced, removed, and renewed; the reproductive process is going on; water is being absorbed or given off;

carbonic acid is being decomposed and carbon absorbed; evaporation is taking place which requires that the root-fibres should take up water, and that by some mysterious means, contrary to gravity and certainly not owing to capillary attraction, the juices of the plant are sent to a distance of sometimes hundreds of feet. All these changes imply motion. So also does the growth of the plant. This is slow indeed in many cases, and particularly in cold or temperate climates, but so rapid in tropical regions where there is abundant moisture in the soil, that plants may almost be seen to grow. This motion is sufficiently powerful to overcome in the majority of cases the force of gravity, and might be measured in foot-pounds. It will also overcome the force of cohesion, as is seen where root-fibres penetrate dense clay or split up solid rock. Motion caused by life alone is seen in the circulation of the blood, and especially in that part of it which takes place in the capillary vessels. If, as I have often done, you snip off the transparent part of the tail of a small fish or a tadpole and place it under the microscope, you may see the blood corpuscles rolling rapidly along for at least half-an-hour; in some cases I have watched them for an hour and a half, still in motion, although during the latter part of the time the motion is much retarded: it seems to continue until some physical change has taken place in the capillaries, the result of their death. If at a suitable temperature suitable pabulum be supplied, the motion of the blood in the capillaries may go on for hours after somatic death has taken place. In some experiments I made a few years ago in New South Wales I found that when portions of tadpoles’ tails placed under the microscope were supplied with a mixture of egg-albumen and water, and kept at a temperature of 80° to 90° F., the circulation continued as long as nineteen hours. The note made at the time is as follows:— “11th (month not mentioned, probably February), 3 p.m. Put four pieces of tadpoles’ tails in albumen and water; they floated; corked the bottle loosely with lint; water was filtered but not boiled. Day hot; temperature 88° F. “Put three other pieces at the same time into some of the same water, in the same kind of bottles stopped in the same way.” “12th, 10 a.m.” (nineteen hours afterwards). “Night had been very hot. Tails placed in water shrivelled slightly (shrunken) and extremity of tail curled up. Under microscope numbers of detached round red corpuscles and quantities of Bacteria; no leucocytes nor cell-growth of any kind.”

“3 p.m. Innumerable monads developed in water surrounding tails; began to smell offensively.” [Thrown away.] Now, contrast this picture of decomposition following somatic death with what took place when the portions of tails were supplied with nutriment. The note is that they “showed no Bacteria either at 10 a.m. or 3 p.m., and, of course, no monads; quantities of young cells, particularly upon and near the cut surface. Circulation slowly continuing in large vessels. In the fluid floating about were quantities of young cells exactly resembling leucocytes.” Even at 10 p.m., although the day was excessively hot, the portion kept under the microscope showed no sign of decomposition. It is evident that this motion of the blood in the smaller vessels cannot be from capillary attraction, for, after the first few moments, the blood in the capillaries must have attained its equilibrium. Place a coloured fluid containing solid non-living particles in a capillary glass tube under the microscope, and you will find that, in a few moments, the particles will be at rest. The following experiment shows the length of time the capillary circulation will continue without nutriment—“10th March, 1878, end of tadpole' tail, circulation continued for thirty-five minutes after separation; not much slower than natural; block at bifurcation of artery; went against gravity.” This note refers to a rough drawing made in my note book of the appearances presented at two periods after the separation of the tail. I have other notes of this phenomenon, but not many, as it was of such invariable occurrence that I soon ceased to note it. It may be seen by anyone who will take a microscope to a slaughterhouse, and obtain a portion of peritonæum or other transparent tissue from animals just slaughtered. In the lower animals the ciliary motion is a very marked and frequent phenomenon. It is chiefly by this that they procure food. It seems to continue without cessation during the whole lifetime of the animal, and to be quite independent of anything like what we recognize as muscular tissue in the higher animals. So also is the curious pulsation in some of the Radiata, the extremely rapid contraction of the stalk of the Vorticella, and the protrusion of the pseudopodia of many other Radiata. All these, and many more that might be mentioned if time permitted, are manifestations of the power of life to produce motion in living protoplasm. The higher animals not only move about by means of their locomotory organs, but in every part of their bodies there is a continual circulation of nutritive fluids, of secretions or of excretions, and there is continual motion of the organs of circulation, respiration, and digestion. In addition to these there is the motion produced by the rapid waste and renewal of tissue that is constantly going on in their bodies.

The major portion of even the obvious muscular movements of the higher animals, such as the vertebrates, is made either independently of the will of the individual, or quite unconsciously, like the automatic motions of the organs of speech in reading aloud when the mind is distracted, etc. Thus breathing is carried on by the action of muscles which in ordinary respiration are not voluntarily exerted. The action of the heart is another example of muscular motion entirely independent of our will. The peristaltic action of the intestines, the action of the sphincters, and the coordination of muscles to retain us in an upright position, are other examples. Muscular contraction and relaxation are therefore going on continuously during life, as are the ciliary movements of some of the mucous membranes. Motion, therefore, is one of the invariable concomitants of life. But it may be said that this is merely the result of the conversion of other forces into motion. I. There are two arguments which seem to me conclusive against this view. The first is that organic motion is carried on to a large extent in opposition to the other forces, especially to gravity, cohesion, and chemical affinity. Many of the higher Vertebrata afford striking examples of the opposition between the action of the muscles and gravity. The usual position of these animals when living and awake is rarely maintained if they are suddenly killed. It may be said that this arises from relaxation of the muscles of the limbs. But when an ox is pithed—that is, suddenly killed by dividing the spinal cord as it issues from the skull—the muscles are not relaxed, but are thrown into violent tetanic convulsions—yet the animal drops instantly. In the same way if a fowl is killed by suddenly beheading it, the headless trunk flutters and springs about for several minutes, but it never stands upright for a moment. You could not make a human skeleton stand upright even if all the joints were stiffened by the ligaments being allowed to dry on them. The fact that even when we are standing upright we are unconsciously balancing ourselves is shown in certain cases of disease of the spinal cord, by blindfolding the patient and then asking him to step out a few paces. He will fall if not supported, because he cannot see where to place his feet. In the healthy state the coordination of the muscles required for balancing ourselves takes place unconsciously. II. In considering the question whether the force which endows protoplasm with these powers is of a special kind, or merely a combination of the other forces or energies of nature, we must remember that a mere blind or unintelligent combination of forces would never produce the results we

see. The process by which a seed becomes a tree, producing other seeds like that from which it sprang, is clearly not the result of any one single force, unless we assume that that force was created and designed ad hoc; neither heat, nor motion, nor light, nor electricity, nor chemical affinity, could alone cause the growth of a tree from a seed. Expose a seed to an amount of heat which will kill it without changing its chemical composition, and all the forces of nature will not enable that seed to germinate. What then do we kill? Even suppose that a living seed, exposed to the influence of heat and moisture, will swell by the mechanical process of endosmosis, suppose even we allow that the ovule will germinate, what possible combination of these or any other forces could make the radicle invariably push its way downwards into the soil, and the plumule as invariably thrust itself upwards towards the light? What combination of forces acting mechanically and without intelligence could enable the cells of the young part to differentiate themselves and form the various tissues of which the plant is composed. Forces such as light and heat must always act under similar circumstances in the same way, unless guided and directed by a Supreme Intelligence. We are therefore driven, as it seems to me, to the conclusion that the force or energy which produces the phenomena that we collectively designate life, must be a force or energy of a special kind, created, if I may be allowed such an old-fashioned expression, ad hoc. In other words, that there is a vital force, which, acting on protoplasm, enables it to move to nourish itself, and to reproduce its like. I need say nothing about the other two qualities which enter into the definition of living matter—self-nutrition and reproduction—as it is nowhere disputed that these powers belong exclusively to living matter. Though, as I think, I have proved the vital force is a distinct and special force, it has so much relation to the other forces of nature as to be convertible into them. Thus in warm-blooded animals it is convertible into heat. That their animal heat is not the mere product of the chemical actions going on in their bodies is proved by the fact that precisely the same actions are going on in cold-blooded animals which do not maintain themselves at a heat above that of the surrounding media. The muscular movements of a lizard, for instance, in the tropics are extremely active, far more so than those of most of the warm-blooded vertebrates—yet the lizard is much cooler than the surrounding atmosphere. We see another proof that the vital force of warm-blooded vertebrates is converted into heat, in the extreme difficulty of maintaining the animal heat of those who are weakly. Among human beings we who are practical physicians have constantly to recognize this fact. The same external temperature which is pleasant and even inspiriting to persons in vigorous health is depressing and injurious, and indeed often fatal, to those who are weak.

Vital force may be converted into electricity, as we see in the Gymnotus or electrical eel, and with light, as we see in the glow-worm, the firefly, the phosphorescent animalcula of the sea. It would seem probable, however, that for the most part the vital force of the higher and more complex organisms is simply transferred by their death to lower organisms, of which the germs are always ready at ordinary temperatures to germinate in the tissues of the higher organisms. There seems to be a constant process of transference of vital force from lower organisms to higher ones, and from these to the lower ones again. Some experiments I have recently been making would seem to show that all but the lowest forms of vegetal life are fed by the Bacteria. I have recently been examining a number of different kinds of soil, taken from various heights above the sea-level, some from the tops of the hills near Sydenham, and some from marshy soil, some from ordinary garden mould, some from gravel deposits, and some from clay dug out at a depth of from two feet to three feet nine inches below the surface. I find them all swarming with Bacteria to such an extent that when shaken up with water in a tube, and allowed to rest for a few days, a layer of Bacteria is formed visible to the naked eye, while the supernatant water never becomes clear, but is constantly opalescent from the presence of these minute organisms. Now when we find Bacteria present in such abundance, and that too in soils which have never been exposed to light since the day they were deposited, it is only natural to enquire for what object they exist, or what end they serve. Are they merely the result of the death and decomposition of higher organisms? This can hardly be the case, because if so they would not be found in such abundance, or at such depths below the surface. Several feet below the surface of soil in which only a few weeds or a little grass is growing we find them in myriads. Now we know that these minute beings can but live a few hours, and that when dead they very speedily disappear. A very simple experiment will prove this. Boil a little garden mould for a few minutes for two or three days running, so as to destroy all Bacteria and their germs, and then let it stand a day or two in hot weather, and it will soon begin to smell offensively. May not these Bacteria be intended for the nourishment of higher organisms, animal and vegetable, but chiefly the latter; and may not their abundance explain the fact that the rootlets of plants descend to such depths in search of nourishment? It seems to me highly probable that the rootlets of the higher plants do not receive nourishment directly from the inorganic constituents of the soil, but do so only by means of these Bacteria, which themselves act as feeders and intermediaries between the inorganic

matter of the soil and the roots of the higher plants. I throw this out merely as a suggestion, but I think the question well worthy of further investigation, particularly as I find that these Bacteria are most abundant in clay, the inorganic constituents of which can hardly afford nourishment to the roots which so abundantly penetrate it. The transmutation of vital force would then seem to go in a perpetual circle—the higher organisms deriving theirs originally from their parent forms, and then constantly recruiting it, as it is dissipated or converted into other forces, from the lower forms, and then giving it back to these in the process of transformation, decay, or death. I believe that the numerous discoveries of Bacteria made of late years in morbid products of the human body, in the bodies of the higher vertebrates are merely expressions of this fact; that the Bacteria are simply the results of the morbid processes, and not their causes. All diseased or unhealthy tissues are in a state of incipient death—their mode of nutrition, their process of growth and development not being the normal ones, they are more likely to become the nursery grounds of Bacteria than the healthy tissues are, which have an inherent power of resisting the presence of these lower forms of life; but to enter fully into this subject would lead me too far from the main question of this paper. To conclude then, I maintain that,— 1st. A living being is a form of protoplasm which possesses within itself the power of motion not derived ab extra, of self-nutrition, and of reproduction. 2nd. That the force or combination of forces which gives to protoplasms these qualities and powers is called life. 3rd. That, if life results from a combination of forces, these must be endowed with intelligence, and act towards a common end. 4th. That the ordinary forces of nature—such as light, heat, chemical affinity, gravity, motion, and the others—are not thus endowed. 5th. That therefore the force which we call for convenience the vital force is a distinct and special force.