THE PROCESSES OF LIFE REVEALED BY THE MICROSCOPE; A PLEA FOR PHYSIOLOGICAL HISTOLOGY.1

By SIMON HENRY GAGE, B. S.,

Of Ithaca, N. Y.

It is characteristic of the races of men that almost at the dawn of reflection the first question that presses for solution is this one of life— life as manifested in men and in the animals and plants around them. What and whence is it, and whither does it tend? Then the sky with its stars, the earth with its sunshine and storm, light and darkness, stand out like great mountain peaks demanding explanation. So in the life of every human being, repeating the history of his race, as the evolutionists are so fond of saying, the fundamental questions are first to obtrude themselves upon the growing intelligence. There is no waiting, no delay for trifling with the simpler problems; the most fundamental and most comprehensive come immediately to the fore and alone seem worthy of consideration. But as age advances most men learn to ignore the fundamental questions and to satisfy themselves with simpler and more secondary matters, as if the great realities were all understood or nonexistent. No doubt to many a parent engaged in the affairs of society, politics, finance, science, or art, the questions that their children put, like drawing aside a thick curtain, bring into view the fundamental questions, the great realities; and we know again that what is absorbing the power and attention of our mature intellect, what perhaps in pride we feel a mastery over, are only secondary matters after all, and to the great questions of our own youth, repeated with such earnestness by our children, we must confess with humility that we still have no certain answers. It behooves us, then, if the main questions of philosophy and science can not be answered at once, to attempt a more modest task, and by studying the individual factors of the problem to hope ultimately to put these together and thus gain some just comprehension of the entire problem.

This address is, therefore, to deal, not with life itself, but with some of the processes or phenomena which accompany its manifestations. But it is practically impossible to do fruitful work according to the Baconian guide of piling observation on observation. This is very

Address of the president of the American Microscopical Society. Printed in Transactions of the American Microscopical Society, Vol. XVII, 1896, pages 3-29.

liable to be a dead mass, devoid of the breath of life. It is a wellknown fact that the author of the Novum Organuon, the key which Bacon supposed would serve as the open sesame of all difficulties and yield certain knowedge, this potent key did not unlock many of the mysteries of science for its inventor. Every truly scientific man since the world began has recognized the necessity of accurate observation, and no scientific principle has ever yet been discovered simply by speculation; but every one who has really unlocked any of the mysteries of nature has inspired, made alive his observations by the imagination; he has, as Tyndall so well put it, made a scientific use of the imagination and created for himself what is known as the "working hypothesis." It must be confessed that for some investigators the "hypothesis" becomes so dear that if the facts of nature do not conform to the hypothesis, "so much the worse for the facts." But for the truly scientific man the hypothesis is destined solely to enable him to get the facts of nature in some definite order, an order which shall make apparent their connection with the great order and harmony which is believed to be present in the universe.

If the working hypothesis fails in any essential particular, he is ready to modify or discard it. For the truly inspired investigator one undoubted fact weighs more in the balance than a thousand theories.

At the very threshold of any working hypothesis for the biologist, this question as to the nature of the energy we call life must be considered. The great problem must receive some kind of a hypothetical solution. What is its relation to the energies of light, heat, electricity, chemism, and the other forms discussed by the physicist? Are its complex manifestations due only to these, or does it have a character and individuality of its own? If we accept the ordinarily received view of the evolution of our solar system, the original fiery nebula, in which heat reigned supreme, slowly dissipated part of its heat, and hurled into space the planets, themselves flaming vapors, only the protons of the solid planets. As the heat became further dissipated there appeared in the cooling mass manifestations of chemical attraction, compounds, at first gases, then liquids, and finally, on the cooling planets, solids appeared. Lastly upon our own planet, the earth, when the solid crust was formed and the temperature had fallen below the boiling point of water, the seas were formed and then life appeared. Who could see, in the incandescent nebula, the liquids and solids of our planet and the play upon them of chemism, of light, heat, electricity, cohesion, tension, and the other manifestations so familiar to all? And yet, who is there that for a moment believes that aught of matter or energy was created in the different stages of the evolution? They appeared or were manifested just as soon as the conditions made it possible. So it seems to me that the energy called life manifested itself upon this planet when the conditions made it possible, and it will cease to manifest itself just as soon as the conditions become sufficiently

unfavorable. It was the last of the forms of energy to appear upon this planet and it will be the first to disappear.

In brief, it seems to me that the present state of physical and physiological knowledge warrants the assumption, the working hypothesis, that life is a form of energy different from those considered in the domain of physics and chemistry. This form of energy is the last to appear, last because more conditions were necessary for its manifestations. It, like the other forms of energy, requires a material vehicle through which to act, but the results produced by it are vastly more complex. Like the other energies of nature, it does not act alone. It acts with the energies of the physicist, but as the master; and under its influence the manifestations pass infinitely beyond the point where for the ordinary energies of nature it is written "thus far and no farther."

It can be stated without fear of refutation that every physiological investigation shows with accumulating emphasis that the manifestations of living matter are not explicable with only the forces of dead matter, and the more profound the knowledge of the investigator the more certain is the testimony that the life energy is not a mere name. And, strange to say, the physicist and the chemist are most emphatic in declaring that life is an energy outside their domain.

The statements of a chemist, a physicist, and a biologist are added. From the character and attainments of these men, their testimony, given after years of the most earnest investigation and reflection, is worthy of consideration:

When a celebrated chemist was asked if he believed that a leaf or a flower could be formed or could grow by chemical forces, he answered:

I would more readily believe that a book on chemistry or on botany could grow out of dead matter by chemical processes.-Liebig.

The influence of animal or vegetable life on matter is infinitely beyond the range of any scientific inquiry hitherto entered on. Its power of directing the motions of moving particles, in the demonstrated daily miracle of our human free will, and in the growth of generation after generation of plants from a single seed, are infinitely different from any possible result of the fortuitous concourse of atoms; and the fortuitous concourse of atoms is the sole foundation in philosophy on which can be founded the doctrine that it is impossible to derive mechanical effect from heat otherwise than by taking heat from a body at a higher temperature, converting at most a definite proportion of it into mechanical effect, and giving out the whole residue to matter at a lower temperature. Sir William Thomson (Lord Kelvin).

The anagenetic [vital] energy transforms the face of nature by its power of assimilating and recompounding inorganic matter, and by its capacity for multiplying its individuals. In spite of the mechanical destructibility of its physical basis (protoplasm) and the ease with which its mechanisms are destroyed, it successfully resists, controls, and remodels the catagenetic [physical and chemical] energies for its purpose.-Cope.

What, then, are the manifestations of the life energy? and what are the processes which are discernible? All of us, in whatever walk of life, will recognize the saying of Gould:

Now, when one looks about him the plainest, largest fact he sees is that of the distinction between living and lifeless things.

As life goes on and works with power where the unaided eye fails to detect it, the microscope-marvelous product of the life energy in the brain of man-shows some of these hidden processes. It has done for the infinitely little on the earth what the telescope has done for the infinitely great in the sky.

Let us commence with the little and the simple. If a drop of water from an aquarium, stream, or pool is put under the microscope many things appear. It is a little world that one looks into, and like the greater one that meets our eye on the streets, some things seem alive and some lifeless. As we look we shall probably find, as in the great world, that the most showy is liable in the end to be the least interesting. In the microscopic world there will probably appear one or more small rounded masses which are almost colorless. If one of these is watched, lo! it moves, not by walking or swimming, but by streaming itself in the direction. First a slender or blunt knob appears, then into it all of the rest of the mass moves, and thus it has changed its posi tion. If the observation is continued, this living speck, which is called an amoeba, will be seen to approach some object and retreat, indeed, it comports itself as if sensitive, with likes and dislikes. If any object suitable for food is met in its wanderings the living substance flows around it, engulfs it and dissolves the nutrient portions and turns them into its own living substance; the lifeless has been rendered alive. If the eye follows the speck of living matter the marvels do not cease. After it has grown to a certain size, as if by an invisible string, it constricts itself in the middle and finally cuts itself in two. The original amœba is no more, in its place there are two. Thus nearly at the bottom of the scale of life are manifested all of the fundamental features— the living substance moves itself, takes nourishment, digests it and changes nonliving into living substance and increases in size; it seems to feel and to avoid the disagreeable and choose the agreeable, and finally it performs the miracle of reproducing its kind, of giving out its life and substance to form other beings, its offspring.

It is the belief of many biologists that the larger and complex forms, even up to man himself, may be considered an aggregation of structural elements originally more or less like the amaba just described; but instead of each member of the colony, each individual itself carrying on all the processes of life independently, as with the amoeba, there is a division of labor. Some move, some digest, some feel, think, and choose, some give rise to new beings, all change lifeless matter into their own living substance. (See Plate XI.)

The processes and phenomena by which a new individual is produced are included under the comprehensive term embryology.