THE WAYS OF LIFE
CHAPTER I
LIFELESS AND LIVING MATTER
GENESIS OF THE UNIVERSE
To the ancients the elements were four-earth, air, fire, and water. Modern science, however, has revealed to us many elemental substances, rarely found free, almost invariably compounded with others in more or less complex union. The ancient earth includes a host of these compounds, the air a mixture of elements, water an extremely simple combination of two gaseous elements, and fire is merely the visible manifestation of a chemical union in the process of becoming.
By means of that scientific marvel, the spectroscope, which can analyze the light emanating from the uttermost limits of the visible universe, we are given to know the elemental content of thousands of heavenly bodies-all, in fact, from which the light can reach our instrument-and in but a single instance has an unknown element been found which has not also been discovered, either in the earth itself, or in its gaseous envelope. Our earth, therefore, is as
rich in possibilities as are any other parts of the realm of nature-richer in many ways, for she is endowed not alone by the material of nature, but with beings formed of so subtle a combination of several of these same elements as to manifest that marvelous series of phenomena, the sum total of which we call life. This does not deny the possibility of life other than on our globe, but such existence is not yet proven, and the true scientist is not given to overmuch speculation.
The elemental substances that make up our earth and our fellow organisms, as well as ourselves, are universal in their occurrence, but whether finite or infinite in their distribution in both space and time science does not say, for all of our theories of earth origin postulate the existence of this elemental matter and its endowment with those various manifestations of energy-chemical affinity, gravity, heat, light, and electricity-about the origin of which science is silent, for it cannot answer questions of ultimate causation. If these are the result of a Creation by an Infinite Being, the time of that Creation must have been immeasurably remote, for it is difficult for the human mind to grasp the conception of an utter and limitless space containing absolutely nothing. The mind can well conceive of chaos, not in its ancient sense of an empty void, but as the confused, unorganized, widely diffused, matter before its orderly arrangement into the heavenly bodies and this mundane sphere. And no conception of the evolution of the universe brought forth by scientific minds can go back of that.
Conception of the Universe and Solar Systems
Of the form of our universe the most generally accepted idea is that it is comparable to one of the stellar nebulae which are resolved by the spectroscope (which readily distinguishes between the light of glowing gaseous material, on the one hand, and of incandescent solids, on the other) into clusters of stars at immeasurable distances from the observer. It is supposed that in looking toward the so-called Milky Way one is looking in the plane of this huge nebula, while in gazing where the stars are few one looks in the direction of its short diameter. The sun is supposed to occupy the approximate center of this system, the general form of which is like a vast disk with a bulging middle. The sun is generally conceived of as derived from a nebulous mass of diffused material, extending through a space greater than that occupied by the present solar system. This nebulous material was so diffused that the residual matter left in the most perfect man-made vacuum is dense compared with it. As a result of gravity there occurred a greater and greater condensation until the astral stage was reached, as stars are immense bodies of luminous gas. Further condensation, despite the fact that it was accompanied by a constant radiation of heat into space, resulted, nevertheless, in a smaller and hotter sun. The fate of this sun would be ultimate cooling of the outer part, with a consequent diminution of its light-giving power until it faded into invisibility as a dead star.
The older Laplacian hypothesis of planet evolution, including the origin of our earth, is well known.
This has, however, been shown to be untenable because of a number of unanswerable objections. As a substitute, Chamberlin and Moulton have offered their planetesimal theory, which, while not of universal acceptance, seems to meet the objections to the older hypothesis. It will, however, require years of testing and amendment before it can be accepted as final. To show how far removed they are from primal causes, their hypothesis is silent concerning solar origin and postulates the primal sun already formed and apparently already having had an existence inconceivably long. This sun has as yet no planetary family, and the means whereby the latter is formed and the substance of its origin are from the primal sun itself. This they believe to have been disrupted by the explosive tidal force, induced by the relatively near passing of another star. What star it was which brought about this catastrophe, ages remote, which was to be of such great importance to future humanity, we do not know, nor of its subsequent fate have we the least idea, but the hypothesis imagines the effect upon our sun in the following manner. The attractive or gravitational force is not the only one in celestial mechanics, but another prodigious force exists, a repellant one, due in part to electric phenomena and manifest in the streaming of a comet's tail, not in the wake of the comet, but away from the sun. Another manifestation of this force lies in the solar prominences which are visible during a total eclipse and rise to the height of hundreds of thousands of miles with incredible velocity. Earth tides are also of a disruptive nature, but are too weak to be destructive. The solar catastrophe of which we
speak was due to tidal disruption, caused by the passing of the other body, matter from the sun being forcibly ejected to a tremendous distance from its diametrically opposite sides. Some of this material got beyond solar control, other parts of it were drawn back into the parent body again, while a relatively small percentage did neither and remained between the sun and outer space, in the form of a two-armed spiral nebula, with the sun at its center. More than one hundred and twenty thousand comparable spiral nebulae are observable in the heavens to-day, while seven hundred thousand nebulae of all sorts have been recorded on photographic plates. The material of such a nebula moves as individual particles, called planetesimals, each in its own orbit, and thus the general form is maintained. Within the arms were knots of matter which were the nuclei of the future planets. Of these the four nearest the sun, one of which was double, were to form the minor planets, Mercury, Venus, Earth-Moon, and Mars, while the four outermost were the nuclei of the major planets, Jupiter, Saturn, Uranus, and Neptune. The influence of these nuclei gave rise to local convergence through gravity, by which other planetesimals were added to the mass already acquired, and by this means the planets grew. The world knot lay in a maze of such planetesimals, which, as their orbits crossed that of the earth, collided with it continuously and were absorbed into its mass, causing it gradually to increase in size, until it had swept its own orbit practically clear. The same would of course be true of the other planets. The region of the asteroids possessed no nucleus; instead, there-
fore, of being concentrated into a ninth planet, they yet persist as relatively small independent bodies, varying in size from five to two hundred or more miles in diameter.
This hypothesis of earth origin does not postulate a molten globe at any stage beyond the nuclear, but rather that it was built up as a solid body. This is Chamberlin's belief. He further holds that it began to possess oceans when about one-third of its present mass. But Chamberlin imagines a growth from the infall of planetesimal dust. Barrell, on the other hand, held that some of the planetesimals, at any rate, were larger, sufficiently so to impart to the earth the energy of their concussion, which would render it molten up to the completion of its growth. In this they were aided by the heat generated by the compression of the deeper nucleus, as well as by their impact. Barrell went on to picture the gradual cooling of the outer crust, but whether the center was solid or fluid during earth growth he did not know The great rigidity of the earth, however, which is equal to that of steel, makes it very unlikely that the interior is molten to-day. Ultimately the ocean waters gathered into basins, which in turn are due to differences in density of the earth's crust, caused by the weighing down of great areas by primordial lava flows. Thus the gathering together of the waters under the heavens and the appearance of the dry land was an extremely ancient happening, and the consequent assumption is that there has been but little shifting of continent and ocean, other than coastal changes, from that period to this, for it is possible that the ocean basins began to form as fast as the
waters gathered, so that some land always existed above the level of the primordial seas.
The establishment of lands and seas, therefore, made possible the atmospheric changes necessary for the establishment of life. The maintenance of internal heat of the earth seems due, in part, at any rate, to the radioactivity of some of its contained material. Barrell has estimated that the heat emanating from a given quantity of uranium in degenerating through radium to stable lead is more than one million times that of an equal weight of coal. The ultimate fate of the sun is of course cooling to extinction, unless, and the possibilities are extremely remote, it undergoes another rejuvenescence through the influence of a passing star. But the solar heat is not maintained by combustion, as the sun is not burning in the ordinary sense, nor is it simply the heat induced during the original formation of the solar orb, for, if such were the case, it would cool in a relatively brief time, compared with its apparent age. It is supposed that at least two factors are responsible for the upkeep of its wonderful source of life-giving heat and light-one the gradual shrinkage of the entire mass, due to gravity, and the other the production of energy, as in the case of the earth, through the degeneration of radioactive substances. None of the planets is now incandescent in the sense that the sun is; even the most brilliant, from our point of view, Venus and Jupiter, shine entirely by reflecting to our eyes the light of the sun.
To sustain life the earth's atmosphere must serve a dual purpose. The supply of oxygen, carbon dioxide, and water must be present in certain proportions
for vital activities. The other function is to act as a blanket to prevent the too rapid radiation into space at night of the solar heat absorbed by the earth during the day. In the atmosphereless moon the change from a scorching heat to the cold of interstellar space must be instantaneous with the setting of the sun.
It does not seem to have been necessary, however, for the production of lower forms of life that the oceans and lands should be completely formed; living organisms, therefore, may well have begun their evolution at an extremely remote period of time.
Living and Non-Living Matter
The distinction between living and non-living matter is not one of material, for precisely the same elements are found in life stuff from the simplest to the most exalted of beings as are found in the lifeless world. The elements thus far recorded as actually pertaining to living matter are comparatively few--carbon, hydrogen, oxygen, nitrogen, sulphur, iron, phosphorus, calcium, fluorine, iodine, magnesium, chlorine, silicon, sodium, potassium, manganese and questionably, lithium. Except for oxygen and nitrogen, none of these substances is found free; some, as in water, are in rather simple compounds, yet other are in combinations so complex that the final analysis of them may never be made with certainty. There is no evidence whatever for the existence of any vital element upon which the manifestation of life depends, for dead protoplasm loses not a particle of weight as compared with that which has all its vital activities in full swing.
The distinction between the living and non-living,
by which is meant that which never has had life, is not in the elemental substances which enter into the living material, but merely in the way in which they are combined, the enormous size and complexity of the resultant molecules, and the consequent physiological or functional properties which they display. There is one compound or group of compounds which is absolutely diagnostic of life stuff in that the substances are never found under any circumstances other than in the bodies of organism, living or dead. These are the proteins, composed of carbon, hydrogen, oxygen, and nitrogen, with traces of other elements, such as sulphur. The molecules of protein are so complex that their atoms, instead of being numbered by the twos or threes, as in so many chemical substances, are actually in the thousands. Protein is an absolutely essential constituent of protoplasm, which in its turn is the primary building material of all organisms of whatsoever sort, whether plant or animal. Other organic compounds, in addition to the proteins, are the fats and oils, and the starches and sugars. None of these substances occurs in nature except as an organic product. There are, in addition, several other materials, such as water, common salt, and the various skeleton- or shell-forming substances, containing lime, or silica.
But protoplasm seems to be more than a mere collection of compounds, however intricate. It is an organized substance and, as such, as much beyond the grade of elaboration of the ordinary substances found in the inorganic world as a trained army is above an unorganized mob, both in its perfection of the relationship of the component elements and
in what are known as its functions, the various activities which its detailed organization brings about.
Analysis of this protoplasm has been attempted repeatedly, with varying results, due in part to the complexity of the material itself, and in part to the fact that its precise structure varies. This is certainly true, physically and probably chemically, for, as Woodruff has said, the protoplasm of one form differs from that of another, it differs in various portions of the same form, and in the same part at different times. If protoplasm were everywhere alike, all organisms would be precisely similar, whereas, as a matter of fact, there is infinite variation.
Much of the chemical content of protoplasm can be learned from its intake and outgo. But while this gives a quantitative conception of its substance, it does not aid in unraveling its structural complexity.
Physiologically it possesses properties which are distinctively vital, as compared with the inertness of the inorganic, such as sensitivity, conductivity, and irritability, whereby stimuli are received, transmitted, and responded to throughout the cell, for the cell is the unit of structure in the form of which protoplasm invariably appears. It also possesses a streaming or other movement, which is not, however, exclusively organic, and co-ordination, which prob-
ably is. Whether it possesses volition or the power to initiate impulses without external stimulus is a moot point. Certainly this seems to be characteristic of the higher animal, and, as the higher animal functions are merely the sum total of those of the cell, it would seem as though volition must be fundamentally resident in protoplasm itself, yet it is probably not manifest in forms which have not as yet evolved a nervous system. Yet other functions are those concerned with nutrition-constructive, whereby the protoplasm takes in appropriate food and, by a certain elaboration, converts it into material similar to itself, which is disseminated throughout its mass, not merely added externally as a crystal grows; or it may be destructive, resulting in the production of simpler compounds out of protoplasm, such a carbon dioxide, water, and ammoniacal salts.These, however, are the by-products, the prime result being the liberation of energy, which manifests itself variously, as mechanical motion, heat, and sometimes light and electricity. Should the upbuilding exceed the waste, the result will be increase of size, or growth; if the reverse be true, diminution. The processes may go on simultaneously and constitute what is generally known as metabolism, which includes both the constructive and destructive aspects of chemical change. As a result of this metabolism an organism is capable of self repair to a varying extent.
Speaking broadly, the cell of typical shape has an external surface, which increases during growth with the square of its diameter; the volume, on the other hand, increases with the cube. Thus, if one of two
spheres has twice the diameter of the other, it will have eight times the mass, but only four times the surface. As the need of food is in direct proportion to the volume, and the ability to absorb it, especially oxygen, carbon dioxide, and the like, to the external surface, it is evident that sooner or later an equilibrium will be reached beyond which growth cannot extend. This balance between food-getting ability and the need for it determines the optimum of size to which, under normal conditions, the cell may attain. But growth, while inhibited in a certain sense, is not at an end, for by an apparently simple process of cell division, a mere dividing into two, the total volume is not lessened, but the surface is largely increased. Hence, once again, the latter is more than sufficient to supply food for the mass, and again growth ensues, until a second optimum is reached. And under certain very ideal conditions, as with Woodruff's pedigreed cultures of the slipper animalcule, Paramecium, this process may continue indefinitely. But the amazing thing is that by this simple method of handing on life and substance to daughter cells, the mother cell merely merges her identity with her life and substance into her offspring.Death has not intervened, nor can it in a line which endures. Accidental death is, of course, possible, but that ends the line; on the other hand, death has never occurred in the direct ancestry of any cell which exists to-day and arises as the result of the complete division of its parent cell.
Protoplasm thus possesses, among the other marvelous properties which differentiate it from the
inorganic world, a potential immortality, so that each living organism on earth to-day is directly and materially connected by the slenderest of threads with an antiquity so vast as to date from the beginning of life on our planet. This attenuated thread is more enduring than anything save the earth and sea. Most of the very rocks themselves, even the mightiest mountain ranges, cannot compare with it.
One marked contrast between the organism and an inorganic thing is the changelessness of the latter, as compared with the former. A crystal of salt forms to-day according to certain mathematical principles; thus it has formed time out of mind; there is no way of telling the age of a mineral crystal from its form. It may increase in size, but that is all; and it may lie in the earth without even this alteration through countless ages.
Organisms, on the other hand, are constantly changing, although here certain groups, genera, and species become stereotyped, so that time has little or no influence upon their structure, so long as their living conditions remain the same.Protozoa alive to-day have been Protozoa since the Archeozoic age and apparently can become nothing else, as the Archeozoic environmental conditions have continued and probably will continue as long as life endures. As a rule, however, animals and plants do change, as a result of the evolutionary process, and their changes are so ordered by certain laws we have yet to discuss that the results are often predictable, and one can judge the age of the creature in geologic time by the characters which it shows.
