Organic evolution

“ Evidently organic evolution, whether individual or general, must always and everywhere have been subordinate to these physical necessities. Though natural selection, beginning with minute portions of protoplasm, must all along have tended to establish a molecular composition apt to undergo this differentiation of surface from centre to the most favourable extent, yet it must all along have done so while controlled by this process of direct equilibration. ”

“ Thus Part I. deals with organic matter and its activity or metabolism, the action and reaction between organisms and their environment, the correspondence between organisms and their circumstances, and similar general data. Part II. states the big inductions regarding growth, development, adaptation, heredity, variation, and so on. Part III. deals with the arguments suggestive of organic evolution and with the factors in the process. Part IV. is a detailed interpretation of the evolution of organic structure, and Part V. an analogous interpretation of the evolution of functions. ”

“ So that this class of connexions between animals and vegetals must have been established since carboniferous times—a period long, indeed, but far shorter than that which organic evolution at large has occupied. ”

“ Each organism exhibits, within a short time, a series of changes which, when supposed to occupy a period indefinitely great, and to go on in various ways instead of one way, give us a tolerably clear conception of organic evolution at large. In an individual development, we see brought into a comparatively infinitesimal time, a series of metamorphoses equally great with each of those which the hypothesis of evolution assumes to have taken place during immeasurable geologic epochs. A tree differs from a seed in every respect—in bulk, in structure, in colour, in form, in chemical composition. ”

“ Organic evolution is a matter of structure and activity. If the structure or the activity be not attuned to the environing conditions, it will be eliminated, those sufficiently well attuned surviving. Turning to the metakinetic aspect, we have seen that there are certain mental processes which are directly and closely associated with activities. Their evolution will be intimately associated with organic evolution. For if these processes lead to ill-attuned activities, the organism will be eliminated ”

“ Darwin, and traced out by him with so much care and skill, can we conclude that, taken alone, it accounts for organic evolution? Has the natural selection of favourable variations been the sole factor? On critically examining the evidence, we shall find reason to think that it by no means explains all that has to be explained. Omitting for the present any consideration of a factor which may be distinguished as primordial, it may be contended that the above-named factor alleged by Dr. Erasmus Darwin and by Lamarck, must be recognized as a co-operator. ”

“ Thus, setting out with inductions from the experiences of organic chemists at the one extreme, and with inductions from the observations of biologists at the other extreme, we are enabled to deductively bridge the interval—are enabled to conceive how organic compounds were evolved, and how, by a continuance of the process, the nascent life displayed in these becomes gradually more pronounced. ”

“ There is also a scientific classification of the subject, into sub-organic, organic, and super-organic evolution. Sub-organic evolution applies to the development of non-living matter; organic, to the development of vegetable and animal life ”

“ Selection acts accordingly as the regulative factor of organic evolution—so in last analysis variations become "the accomplishment of that which variability permits, environment requires, and selection directs." To be noted also is the fact that variability, or the tendency to vary under environmental conditions, is counteracted to a considerable extent by heredity, or the tendency to breed true, the former being the progressive, the latter the conservative, principle of organic evolution.
Man himself is an animal, the final product, apparently, of organic evolution. ”

“ Therefore, natural selection has always to wait and to watch for such variations of germ-plasm as will eventually prove beneficial to the individuals developed therefrom, who will then transmit this peculiar quality of germ-plasm to their progeny, and so on. Therefore also—and this is most important to remember—natural selection as thus working becomes the one and only cause of organic evolution in all the multicellular organisms, just as the direct action of the environment is the one and only cause of it in the case of all the unicellular organisms. ”

“ On the contrary, there is the best evidence to show that since the first dawn of life in the occurrence of the simplest organisms, until the meridian splendour of life as now we see it, gradual advance from the general to the special—from the low to the high, from the few and simple to the many and complex—has been the law of organic nature. And of course it is needless to say that this is precisely the law to which the process of descent with adaptive modification would of necessity give rise. ”

“ But whatever the order of arrangement, there can be no doubt of this: these several races and numerous varieties of mankind represent so many organic variations of the human species, effected through the interaction of variability and environment, and established by adaptation and selection. Now each of these races and every variety of the human species has contributed something to the sum total of civilization. So it seems, in man's case, the line of organic evolution is succeeded and supplemented by a line of super-organic development. ”

“ Stated concretely in regard to living creatures, the general doctrine of organic evolution suggests, as we all know, that the plants and animals now around us—with all their fascinating complexities of structure and function, of life-history, behaviour, and inter-relations—are the natural and necessary results of long processes of growth and change, of elimination and survival, operative throughout practically countless ages ”

“ In the absence of that cyclical series of metamorphoses which even the simplest living thing now shows us, as a result of its inherited constitution, there could be no point d'appui for natural selection. How, then, did organic evolution begin?
If a primitive mass of organic matter was like a mass of inorganic matter in respect of its passivity, and differed only in respect of its greater changeableness; then we must infer that its first changes conformed to the same general law as do the changes of an inorganic mass. The instability of the homogeneous is a universal principle. ”

“ And forasmuch as natural selection may thus continue, ad infinitum, slowly to alter a specific type in adaptation to a gradually changing environment, if in any case the alteration thus effected is sufficient in amount to lead naturalists to denote the specific type by some different name, it follows that natural selection has transmuted one specific type into another. And so the process is supposed to go on over all the countless species of plants and animals simultaneously—the world of organic types being thus regarded as in a state of perpetual, though gradual, flux. ”

“ Spencer's position may be more clearly defined if we first sketch the answer which most biologists would at present give to the question—What are the factors of Organic Evolution?
Variation.—Postulating the powers of growing and reproducing, of acting on and reacting to the environment, postulating also heredity without which no organic evolution is possible, biologists distinguish two sets of factors in the evolution process. On the one hand there are originative factors which produce those changes in living creatures which make them different from their fellows. ”

“ As organic forms survive only to the extent to which they are in harmony with each other and with inorganic conditions, so inorganic forms or combinations survive unaltered only when they are in harmony with other inorganic conditions and uninterfered with by organic forms. Matter and motion in some form must survive, both being indestructible. Natural Selection in this sense, as at each moment regulating inorganic combinations and motions and organic form and function, is either ultimately the origin of variation, or else it is not its preserver. ”

“ On this hypothesis of organic combination, to which we shall recur in the chapter on "Organic Evolution," the varied forms of animal life are the outcome of definite organic products with definite organic structure, analogous to the definite chemical compounds with definite crystalline and molecular structure; and the analogy between the regeneration of hydra and the reconstruction of a crystal is carried on a step further. ”

“ If we confine ourselves for the moment to the material side, we find that the directional change in organic evolution can be reduced to this—to an [Pg 254] increase of the control exercised by living matter over the environment, and of its independence of the environment—two reciprocal aspects of a single process. ”

“ It has been again and again pointed out that the phyletic development of the vegetable kingdom proceeds with regularity and according to law, as we see in the preponderance and constancy of so-called purely ‘morphological’ characters in plants. The formation of natural groups in the animal and vegetable kingdoms compels us to admit that organic evolution has frequently proceeded for longer or shorter periods along certain developmental lines. ”

“ The qualification implied by the words in italics is necessary, for it is clearly possible that the external conditions then existing were not suitable for the production of all the stages of the potential life-history, and that what we call organic evolution has consisted in a gradual evolution of new environments to which the organism's innate capacity of change has enabled it to adapt itself. ”

“ Organic evolution takes place only on condition that the masses of protoplasm formed of the physiological units, and of the assimilable materials out of which others like themselves are to be multiplied, are subject to heat of a given degree—are subject, that is, to the unceasing impacts of undulations of a certain strength and period ”

“ The paramount importance of Darwin's contributions to the evidences of organic evolution are [sic] often forgotten in the brilliant theory which he believed to supply the motive cause of descent with modification. Organic evolution had been held to be true by certain thinkers during many centuries ”

“ Returning to the thread of our exposition, we have next to trace, throughout organic progress, this same all-pervading principle. And here, where the evolution of the homogeneous into the heterogeneous was first observed, the production of many effects by one cause is least easy to demonstrate. The development of a seed into a plant, or an ovum into an animal, is so gradual, while the forces which determine it are so involved, and at the same time so unobtrusive, that it is difficult to detect the multiplication of effects which is elsewhere so obvious. ”

“ At a certain time in the earth's history, after the hard outer crust had been formed, it became possible for living materials to arise and for simple primitive creatures to exist. Thus began the process of organic evolution—the natural history of living things—with which we are concerned in this and later addresses. ”

“ Of the party above referred to as not satisfied with this conception described by Professor Huxley, there were two classes. The great majority were admirers of the Vestiges of the Natural History of Creation—a work which, while it sought to show that organic evolution has taken place, contended that the cause of organic evolution, is “an impulse” supernaturally “imparted to the forms of life, advancing them, ... through grades of organization.” ”

“ Our study has led us to the conclusion that in the whole evolution of man, in his embryology and in his phylogeny, there are no living forces at work other than those of the rest of organic and inorganic nature. All the forces that are operative in it could be reduced in the ultimate analysis to growth, the fundamental evolutionary function that brings about the forms of both the organic and the inorganic. But growth itself depends on the attraction and repulsion of homogeneous and heterogeneous particles. ”

“ In zoölogy the environment of an organism means the sum-total of the conditions of life that surround and affect it, such as food, air, water, climate, etc.
We have already stated that as far as evolution is concerned the structures of fundamental importance in an organism are the Germ-Cells; therefore, for our purposes, we will define environment to be the sum-total of the conditions that directly or indirectly influence in any way the germ-cells, by which variations in them may be produced, or through which stability may be maintained. ”

“ That there has been Evolution in one sense of the term is obvious,—that is to say, development of organic types from lower to higher forms, from the sea-weed or fungus to the oak or the rose, from the star-fish or the coral-insect, to the eagle or to man. The question is, not whether there has been such a{206} progressive succession of forms, but whether one form has proceeded from another genetically, being produced in the same manner as individuals of a species now are. That this has been the case, as Professor Huxley tells us in the same address, is the cornerstone of evolutionary teaching. ”

“ Though natural selection must have become increasingly active when once it had got a start; yet the differentiating action of the medium never ceased to be a co-operator in the development of these first animals and plants. Again taking the lead as there arose the composite forms of animals and plants, and again losing the lead with that advancing differentiation of these higher types which gave more scope to natural selection, it nevertheless continued, and must ever continue, to be a cause, both direct and indirect, of modifications in structure. ”