[5] Mr Herbert Spencer's Biology, "Natural Science," xiii. (1898) pp. 377-383.
Much that is in The Principles of Biology has now become common biological property; much has been absorbed or independently reached by others; consciously or unconsciously we are now, as it were, standing on Spencer's shoulders, but this should not blind us to the magnitude of Spencer's achievement. The book was more than a careful balance-sheet of the facts of life at a time when that was much needed; it meant orientation and systematisation; it was the introduction of order, clearness, and breadth of view. It gave biology a fresh start by displaying the facts of life and the inductions from these for the first time clearly in the light of evolution. For if the evolution idea is an adequate modal formula of the great process of Becoming, then we need to think of growth, development, differentiation, integration, reproduction, heredity, death—all the big facts—in the light of this. And this is what the Principles of Biology helps us to do. It is of course saturated with the theory of the transmissibility of acquired characters—an idea integral to much of Spencer's thinking—which had hardly begun to be questioned when the work was published, which is now, however, a very moot point indeed. For this and other reasons, we doubt whether Spencer was wise in making a re-edition of what might well have remained as a historical document, especially as the re-edition is not so satisfactory for 1898 as the original was for 1864.
The chief purpose of The Principles of Biology was to interpret the general facts of organic life as results of evolution. Manifestly, as a preliminary step, "it was needful to specify and illustrate these general facts; and needful also to set forth those physical and chemical properties of organic matter which are implied in the interpretation." "What are the antecedent truths taken for granted in Biology, and what are the biological truths, which, apart from theory, may be regarded as established by observation?" 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. Part VI. deals with the laws of multiplication.
Before illustrating Spencer's workmanship in dealing with these great themes, we cannot but ask what preparation he had for a task so ambitious. He had an inborn interest in Natural History; he had dabbled in Entomology and done a little microscopic work; he had attended lectures by Owen and had enjoyed many a talk with Huxley; he had been influenced by Lamarck, Milne-Edwards, and von Baer; he had read hither and thither in medical and biological literature; but it is manifest that his own admission was true that he was "inadequately equipped for the task." That he succeeded in producing a biological classic is a signal proof of his intellectual strength. He was kept right by his power of laying hold of cardinal facts and by his grip of the Evolution-clue. Not to be forgotten, moreover, was the generous help rendered by Professor Huxley and Sir Joseph Hooker, who checked his proofs. Spencer made but one biological investigation (1865-6), and that of little moment—on the circulation in plants—but his contact with the facts of organic life was by no means superficial. His intelligence was such that he got further into them than most concrete workers have ever done. And in some measure it was an advantage to him in his task that he was no specialist, that he did not know too much. It enabled him to approach the facts with a fresh mind, and to see more clearly the general facts of Biology which lie behind the details of Botany and Natural History. He was in no danger of not seeing the wood for the trees.
Organic Matter.—"In the substances of which organisms are composed, the conditions necessary to that redistribution of Matter and Motion which constitutes Evolution, are fulfilled in a far higher degree than at first appears." Thus the most complex compounds into which Carbon, Hydrogen, Oxygen, and Nitrogen enter, together with small proportions of two other elements (Sulphur and Phosphorus) which very readily oxidise, "have an instability so great that decomposition ensues under ordinary atmospheric conditions"; the component elements have an unusual tendency to unite in different modes of aggregation though in the same proportions, thus forming analogous substances with different properties; the colloid character of the most complex compounds that are instrumental to vital actions gives them great molecular mobility—a plastic quality fitting them for organisation; "while the relatively great inertia of the large and complex organic molecules renders them comparatively incapable of being set in motion by the ethereal undulations, and so reduced to less coherent forms of aggregation, this same inertia facilitates changes of arrangement among their constituent molecules or atoms, since, in proportion as an incident force impresses but little motion on a mass, it is the better able to impress motion on the parts of the mass in relation to one another"; "lastly, the great difference in diffusibility between colloids and crystalloids makes possible in the tissues of organisms a specially rapid redistribution of matter and motion; both because colloids, being easily permeable by crystalloids, can be chemically acted on throughout their whole masses, instead of only on their surfaces; and because the products of decomposition, being also crystalloids, can escape as fast as they are produced, leaving room for further transformations." In short, organic matter is chemically and physically well-suited to be the physical basis of life.
The colloid character of organic matter facilitates modification by arrested momentum or by continuous strain. There is often strong capillary affinity and rapid osmosis. Heat is an important agent of redistribution in the animal organism, and light is an all-important agent of molecular changes in organic substances. But the extreme modifiability of organic matter by chemical agencies is the chief cause of that active molecular rearrangement which organisms, and especially animal organisms, display. In short, the substances of which organisms are built up are specially sensitive to the varied environing influences; "in consequence of its extreme instability organic matter undergoes extensive molecular rearrangements on very slight changes of conditions."
The correlative general fact is that during these extensive molecular rearrangements, there are evolved large amounts of energy, in the form of motion, heat, and even light and electricity. On the one hand the components of organic matter are regarded as falling from positions of unstable equilibrium to positions of stable equilibrium; on the other hand, "they give out in their falls certain momenta—momenta that may be manifested as heat, light, electricity, nerve-force, or mechanical motion, according as the conditions determine." It follows from the law of the Conservation of Energy that "whatever amount of power an organism expends in any shape, is the correlate and equivalent of a power which was taken into it from without."
Metabolism.—"The materials forming the tissues of plants as well as the materials contained in them, are progressively elaborated from the inorganic substances; and the resulting compounds, eaten, and some of them assimilated by animals, pass through successive changes which are, on the average, of an opposite character: the two sets being constructive and destructive. To express changes of both these natures the term 'metabolism' is used; and such of the metabolic changes as result in building up from simple to compound are distinguished as 'anabolic,' while those which result in the falling down from compound to simple are distinguished as 'katabolic.'"
"Regarded as a whole, metabolism includes, in the first place, those anabolic or building-up processes specially characterising plants, during which the impacts of ethereal undulations are stored up in compound molecules of unstable kinds; and it includes, in the second place, those katabolic or tumbling-down changes specially characterising animals, during which this accumulated molecular motion (contained in the food directly or indirectly supplied by plants) is in large measure changed into those molar motions constituting animal activities. There are multitudinous metabolic changes of minor kinds which are ancillary to these—many katabolic changes in plants and many anabolic changes in animals—but these are the essential ones."
Definition of Life.—Spencer's first definition of life (Theory of Population, 1852) was simply "the co-ordination of actions." But he soon saw that this was too wide. "It may be said of the Solar System, with its regularly-recurring movements and its self-balancing perturbations, that it, also, exhibits co-ordination of actions." "A true idea of Life must be an idea of some kind of change or changes." Therefore he carefully considered assimilation on the one hand, as an example of bodily life, and reasoning on the other hand, as an example of that life known as intelligence, and inquired into the common features of these two processes of change. Thus there emerged the formula that life is the definite combination of heterogeneous changes, both simultaneous and successive. But this formula also fails, as he said, by omitting the most distinctive peculiarity. It is universally recognised that living creatures continually exhibit effective response to external stimuli. To be able to do this is the very essence of life, distinguishing its responses from non-vital responses. Thus a clause must be added to the proximate conception, and the formula reads: "Life is the definite combination of heterogeneous changes, both simultaneous and successive, in correspondence with external co-existences and sequences." There are internal relations, namely, "definite combinations of heterogeneous changes, both simultaneous and successive," and there are external relations, "external co-existences and sequences," and life is the connexion of correspondence between them. Thus under its most abstract form, Spencer's conception of Life is:—"The continuous adjustment of internal relations to external relations."
In an appendix to the revised edition of the Principles of Biology, Spencer admits that he had not sufficiently emphasised the fact of co-ordination. "The idea of co-ordination is so cardinal a one that it should be expressed not by implication but overtly." The formula defining the phenomenon of life thus reads: "The definite combination of heterogeneous changes, both simultaneous and successive, co-ordinated into correspondence with external co-existences and sequences." It may be needful to remark that this was not intended to define Life in its essence, but Life as manifested to us. "The ultimate mystery is as great as ever: seeing that there remains unsolved the question: What determines the co-ordination of actions?"