Herbert Spencer

Spencer's historical position in regard to the Evolution-Idea.—In 1840, when Herbert Spencer was twenty, he bought Lyell's Principles of Geology—then recently published. His reading of Lyell was a fortunate incident, for one of the chapters, devoted to a refutation of Lamarck's views concerning the origin of species, had the effect of giving Spencer a decided leaning to them.

"Why Lyell's arguments produced the opposite effect to that intended, I cannot say. Probably it was that the discussion presented, more clearly than had been done previously, the natural genesis of organic forms. The question whether it was or was not true was more distinctly raised. My inclination to accept it as true in spite of Lyell's adverse criticisms, was, doubtless, chiefly due to its harmony with that general idea of the order of Nature towards which I had, throughout life, been growing. Super-naturalism, in whatever form, had never commended itself. From boyhood there was in me a need to see, in a more or less distinct way, how phenomena, no matter of what kind, are to be naturally explained. Hence, when my attention was drawn to the question whether organic forms have been specially created, or whether they have arisen by progressive modifications, physically caused and inherited, I adopted the last supposition; inadequate as was the evidence, and great as were the difficulties in the way. Its congruity with the course of procedure throughout things at large gave it an irresistible attraction; and my belief in it never afterwards wavered, much as I was in after years ridiculed for entertaining it" (Autobiography, i. p. 176).

Thus early convinced, Spencer did not remain a mute evolutionist. The idea was a seed-thought in his mind, and eventually it became the dominant one, bearing much fruit. In his early letters to the "Nonconformist" in 1842 on "The Proper Sphere of Government," "the only point of community with the general doctrine of Evolution is a belief in the modifiability of human nature through adaptation to conditions, and a consequent belief in human progression." But in his Social Statics (1850) there "may be seen the first step toward the general doctrine of Evolution." Thus he says, "The development of society as well as the development of man and the development of life generally, may be described as a tendency to individuate—to become a thing. And rightly interpreted, the manifold forms of progress going on around us are uniformly significant of this tendency."

It was a great moment in Herbert Spencer's intellectual life when in 1851 (ætat. 31) he first came across von Baer's formula "expressing the course of development through which every plant and animal passes—the change from homogeneity to heterogeneity." At the close of his Social Statics Spencer had indicated that progress from low to high types of society or organism implied an advance "from uniformity of composition to multiformity of composition." "Yet this phrase of von Baer, expressing the law of individual development, awakened my attention to the fact that the law which holds of the ascending stages of each individual organism is also the law which holds of the ascending grades of organisms of all kinds. And it had the further advantage that it presented in brief form, a more graphic image of the transformation, and thus facilitated further thought. Important consequences eventually ensued."

Von Baer's formula of embryonic development, which he regarded as a progress from the apparently simple to the obviously complex, and as the individual's condensed and modified recapitulation of racial history, accentuated and stimulated a thought already existing in Spencer's mind, and in part expressed. It gave objective vividness to the concept of development which Spencer had already realised in regard to societary forms. In 1864 he wrote to G. H. Lewis, "If anyone says that had von Baer never written I should not be doing that which I now am, I have nothing to say to the contrary—I should reply it is highly probable."

Herbert Spencer spoke of his early recognition of von Baer's law as one of the moments in his intellectual development. He realised objectively and vividly that out of an apparently simple and homogeneous stage of development, there is developed by division of labour and other processes, a wondrous complexity of nervous, muscular, glandular, skeletal, and connective tissues or organs, as the case may be. Organic development is not like crystallisation; it is heteromorphic crystallisation, so to speak. From a group of apparently similar cells, heterogeneous tissues and organs are developed. Thus von Baer as an embryologist gave Spencer as a general evolutionist a concrete basis for the concept of development which was simmering in his mind.

Von Baer's Law.—It does not appear, however, that Spencer ever read von Baer's embryological memoirs, else he might have been less well-satisfied with summing up individual development as a progress from homogeneity to heterogeneity. Von Baer was much more cautious than some of his followers and expositors, and subsequent research has justified his caution. The once popular "Recapitulation Doctrine" that a developing organism "climbs up its own genealogical tree," that "ontogeny recapitulates phylogeny," is now seen to be true only in a very general way, and with many saving clauses. The germ is now known as a unified mosaic of ancestral contributions, as a multiplex of potentialities; it is even visibly very complex and anything but homogeneous or "simple"; and the individual recapitulation of racial history is verifiable rather in the stages of organogenesis than in the history of the embryo as a whole. Thus while all are agreed that there is a gradual emergence of the obviously complex from the apparently simple, that development means progressive differentiation and integration, and that past history is in some measure resumed in present development, it must also be allowed that germ-cells are microcosms of complexity, that development is the realisation of a composite inheritance, the cashing of ancestral cheques, and that the "minting and coining of the chick out of the egg" is not adequately summed up as "a progress from homogeneity to heterogeneity."

But although embryology does not appear to us to give unequivocal support to Spencer's formula of progress from the homogeneous to the heterogeneous, it seemed all plain sailing to him, and he proceeded to illustrate the utility of his formula by applying it to all orders of facts. In a famous passage in the essay on "Progress: its Law and Cause" (Essays, vol. i., 1883, p. 30) he wrote as follows:—

"We believe we have shown beyond question that that which the German physiologists (von Baer, Wolff, and others) have found to be the law of organic development (as of a seed into a tree and of an egg into an animal) is the law of all development. The advance from the simple to the complex, through a process of successive differentiations (i.e. the appearance of differences in the parts of a seemingly like substance), is seen alike in the earliest changes of the Universe to which we can reason our way back; and in the earlier changes which we can inductively establish; it is seen in the geologic and climatic evolution of the Earth, and of every simple organism on its surface; it is seen in the evolution of Humanity, whether contemplated in the civilised individual, or in the aggregation of races; it is seen in the evolution of Society in respect alike of its political, its religious, and its economical organisation; and it is seen in the evolution of all those endless concrete and abstract products of human activity which constitute the environment of our daily life. From the remotest past which Science can fathom up to the novelties of yesterday, that in which Progress essentially consists is the transformation of the homogeneous into the heterogeneous." This was written in 1857.

As far back as 1852 Spencer contributed to the 'Leader' an essay on the 'Development Hypothesis' which is one of the most noteworthy of the pre-Darwinian presentations of the general idea of evolution. Supposing that there are some ten millions of species, extant and extinct, he asks "which is the most rational theory about these ten millions of species? Is it most likely that there have been ten millions of special creations? or is it most likely that by continual modifications, due to change of circumstances, ten millions of varieties have been produced, as varieties are being produced still?... Even could the supporters of the Development Hypothesis merely show that the origination of species by the process of modification is conceivable, they would be in a better position than their opponents. But they can do much more than this. They can show that the process of modification has effected, and is effecting, decided changes in all organisms subject to modifying influences.... They can show that in successive generations these changes continue, until ultimately the new conditions become the natural ones. They can show that in cultivated plants, domesticated animals, and in the several races of men, such alterations have taken place. They can show that the degrees of difference so produced are often, as in dogs, greater than those on which distinctions of species are in other cases founded. They can show, too, that the changes daily taking place in ourselves—the facility that attends long practice, and the loss of aptitude that begins when practice ceases—the strengthening of passions habitually gratified, and the weakening of those habitually curbed—the development of every faculty, bodily, moral, or intellectual according to the use made of it—are all explicable on this same principle. And thus they can show that throughout all organic nature there is at work a modifying influence of the kind they assign as the cause of these specific differences; an influence which, though slow in its action, does, in time, if the circumstances demand it, produce marked changes—an influence which, to all appearance, would produce in the millions of years, and under the great varieties of condition which geological records imply, any amount of change."

While Spencer did not discern the modifying influence of Natural Selection, which it was reserved for Darwin and Wallace to disclose, his clear presentation of the general doctrine of evolution seven years before the publication of the "Origin of Species" (1859) should not be forgotten.

In other essays before 1858 and in his Principles of Psychology (1855), Spencer championed the evolutionist position, and the first programme of his "Synthetic Philosophy" was drawn up in January 1858.

Arguments for the Evolution-Doctrine.—The idea that the present is the child of the past and the parent of the future, that what we see around us is the long result of time, that there has been age-long progress from relatively simple beginnings—the evolution-formula in short—is now part of the intellectual framework of most educated men with a free mind. We no longer trouble to argue about it; like wisdom it is justified of its children. It has afforded a modal interpretation of the world's history, an interpretation that works well, which no facts are known to contradict. It has been the most effective organon of thought that the world has known; it is becoming organic in all our thinking.

We cannot indeed give an evolutionary account of the origin of life, or of consciousness, or of human reason; we cannot read the precise pedigree of many of the forms of life; we are in great doubt as to the modus operandi by which familiar results have been brought about, but all this ignorance does not diminish our confidence in the scientific value of the general evolution-idea. It may be that there are some primary facts, such as life and consciousness, which we must be content to postulate as at present irresoluble data, but it is also certain that our inquiry into the factors of evolution is still very young. So much has been done in half a century, since serious ætiology began, that it is premature to say ignorabimus where we must confess ignoramus.

It seems possible to give a provisional evolutionist account of so many of "the wonders of life," as Haeckel calls them, that there are few nowadays who will maintain that, given certain postulates, a scientific interpretation of nature is impossible. This is what the doctrine of special creation or creations implies; it means an abandonment of the scientific interpretation of nature as a hopeless task.

If the evolution key failed to open the doors to which we apply it, then there would be justification for a rehabilitation of the creationist doctrine, but the reverse is the case. To some minds, notably Mr Alfred Russel Wallace, the problems of the origin of life, of consciousness, and of man's higher qualities seem so hopelessly far from scientific interpretation, that a combination of evolutionism with a moiety of creationism appears necessary. But as we are only beginning to know the scope and efficacy of the factors of evolution, and are not without hope of discovering other factors, this dualism seems premature.

Evolution and Creation.—But while the Evolution-Doctrine is now admitted as a valid and useful genetic formula, it was far otherwise when Spencer was writing his Principles of Biology (1864-6). Then the doctrine of descent was struggling for existence against principalities and powers both temporal and spiritual, and then it was still relevant to pit it against the theory of special creations. Yet for a younger generation it is difficult to appreciate the warmth of Spencer's chapter on the Special-Creation hypothesis (§ 109-§ 115 of vol. i. of the original edition of The Principles of Biology).

"The belief in special creations of organisms is a belief that arose among men during the era of profoundest darkness; and it belongs to a family of beliefs which have nearly all died out as enlightenment has increased. It is without a solitary established fact on which to stand; and when the attempt is made to put it into definite shape in the mind, it turns out to be only a pseud-idea. This mere verbal hypothesis, which men idly accept as a real or thinkable hypothesis, is of the same nature as would be one, based on a day's observation of human life, that each man and woman was specially created—an hypothesis not suggested by evidence, but by lack of evidence—an hypothesis which formulates absolute ignorance into a semblance of positive knowledge."...

"Thus, however regarded, the hypothesis of special creations turns out to be worthless—worthless by its derivation; worthless in its intrinsic incoherence; worthless as absolutely without evidence; worthless as not supplying an intellectual need; worthless as not satisfying a moral want. We must therefore consider it as counting for nothing, in opposition to any other hypothesis respecting the origin of organic beings."

The appreciation of the evolution-formula in the minds of thoughtful men has been greatly modified—for the better—since the early Darwinian days of hot-blooded controversy, when Spencer was a prominent champion of the new way of looking at things. The special-creation hypothesis has almost ceased to find advocates who know enough about the facts to bring forward arguments worthy of consideration, and by a legitimate change of front on the part of theologians it has come to be recognised that the evolution-formula is not antithetic to any essential transcendental formula. Naturalists, on the other hand, recognise that the Evolution-formula is no more than a genetic description, that it does not pretend to give any ultimate explanations, that as such it has nothing whatever to do with such transcendental concepts as almighty volition, and that it has no quarrel with the modern theological view of creation as the institution of the primary order of nature—the possibility of natural evolution included. Thus Spencer's destructive attack on the Special-Creation hypothesis has now little more than historical interest. And for this result, we have in part to thank Spencer himself, who made the precise point at issue so definitely clear.

The general theory of organic evolution—the theory of Descent—tacitly makes the assumption, which is the basal hope of all biology, that it is not only legitimate but promiseful to try to interpret scientifically the history of life upon the earth. It formulates the idea that the present phase of being is the natural and necessary outcome of a previous, on the whole, simpler phase of being, and so on, backwards and forwards in time, under the operation of more or less clearly discernible natural factors and conditions—notably variation and heredity, selection and isolation. Tested a thousand times, the general evolution-formula seems to cover the facts, it gives them a new rationality, it applies to minutiose details as well as to the general progress of life, it even affords a basis for verified prophecy. The formula is a key that fits all locks, though it has not yet, because of our fumbling fingers, opened all.

But just here, as Spencer pointed out, there is a parting of the ways, and there is no via media, no compromise. Is there no hopefulness in trying to give a scientific account of the nature and history and genesis of the confessedly vast and perplexing orders of facts which we call Physical Nature, Animate Nature, and Human Nature?—then let us become agnostics pure and simple, or let us remain philosophers or theologians, poets or artists, and sigh over an impetuous science which started so much in debt that its bankruptcy was a foregone conclusion!

On the other hand, if the scientific attempt at interpretation is legitimate, and if it has already made good progress (considering its youth), and if its results, achieved piecemeal, always make for greater intelligibility, then let us give the scientific, i.e., evolutionist formulation its due; let us rigidly exclude from our science all other than scientific interpretations; let us cease from juggling with words in attempting a mongrel mixture of scientific and transcendental formulation; let us stop trying to eke out demonstrable factors, such as variation and selection, by assuming alongside of these, "ultra-scientific causes," "spiritual influxes," et hoc genus omne; let us cease writing or reading books such as God or Natural Selection, whose titular false antinomy is an index of the bathos of their misunderstanding. To place scientific formulæ in opposition to transcendental formulæ is to oppose "incommensurables," and to display an ignorance of what the aim of science really is.

Logically, the antithesis is between the possibility or the impossibility of giving a scientific interpretation of the world around us (and ourselves). The hypothesis of special creations is irrelevant until the scientific interpretation is shown to be inadequate or fallacious.

Arguments for the Evolution-Doctrine.—But what, it may be asked, is the evidence substantiating the formula of organic evolution, and compelling us to accept it? To this question, we propose to give in brief resumé Spencer's answer, but it is impossible to refrain from observing that the question involves some measure of misunderstanding. The evolution theory, as a modal formula, is just a particular way of looking at things; it is justified wherever it is applied; it makes for progress whenever it is utilised; but it cannot be proved by induction or experiment like the law of gravitation or the doctrine of the conservation of energy. Fritz Müller said that he would be content to stake the evolution theory on a study of butterflies alone, and he was right. The formula is justified by its detailed applicability; there are not any special evidences of evolution; any set of facts in regard to organisms well worked-out illustrates the general thesis. At the same time, it is possible to classify the different ways in which the Evolution-Idea fits the facts, and this is what Spencer did in his presentation of the "arguments for evolution"—a presentation which has never been surpassed in clearness, though every illustration has been multiplied many times since 1866.

I. The Arguments from Classification. Spencer started with the fact that naturalists have utilised resemblances in structure and development as a basis for the orderly classification of organisms in groups within groups—varieties, species, genera, families, races, and so on. But "this is the arrangement which we see arises by descent, alike in individual families and among races of men." "Where it is known to take place evolution actually produces these feebly-distinguished small groups and these strongly-distinguished great groups." "The impression made by these two parallelisms, which add meaning to each other, is deepened by the third parallelism, which enforces the meaning of both—the parallelism, namely, that as, between the species, genera, orders, classes, etc., which naturalists have formed, there are transitional types; so between the groups, sub-groups, and sub-sub-groups, which we know to have been evolved, types of intermediate values exist. And these three correspondences between the known results of evolution (as in human races, domesticated animals, and cultivated plants) and the results here ascribed to evolution have further weight given to them by the fact, that the kinship of groups through their lowest members is just the kinship which the hypothesis of evolution implies." "Even in the absence of these specific agreements, the broad fact of unity amid multiformity, which organisms so strikingly display, is strongly suggestive of evolution. Freeing ourselves from pre-conceptions, we shall see good reason to think with Mr Darwin, "that propinquity of descent—the only known cause of the similarity of organic beings—is the bond, hidden as it is by various degrees of modification, which is partly revealed to us by our classifications" (Principles of Biology, Rev. Ed. vol. i. p. 448).

II. Arguments from Embryology. Organisms may be arranged on a tree which symbolises their structural affinities and divergences. On the evolutionist interpretation this is an adumbration of the actual genealogical tree or Stammbaum. But when we consider the facts of embryology we find that the developing organism advances from stage to stage by steps which are more or less comparable to the various levels and branchings of the classificatory tree. There is a resemblance, sometimes a parallelism, between individual development and the grades of organisation which have or have had persistent stability as living creatures. "On the hypothesis of evolution this parallelism has a meaning—indicates that primordial kinship of all organisms, and that progressive differentiation of them which the hypothesis alleges. On any other hypothesis the parallelism is meaningless." It is true that there are nonconformities to the general law that individual development tends to recapitulate racial history, or that ontogeny tends to recapitulate phylogeny. There may be in the individual development condensations or telescopings of the presumed ancestral stages, and there may be an interpolation of developmental stages which are adaptive to peculiar conditions of juvenile life and have no historical import, but the deviations are such as may be readily interpreted on the evolution-hypothesis (Principles of Biology, i. pp. 450-467).

III. Arguments from Morphology. In back-boned animals from frog to man there is a great variety of fore-limb, adapted for running, swimming, flying, grasping, and so forth, but throughout there is a unity of structure and development. There are the same fundamental bones and muscles, nerves and blood vessels, and the early stages are closely similar. So it is throughout organic nature; there is unity of type, maintained under extreme dissimilarities of form and mode of life. This is "explicable as resulting from descent with modification; but it is otherwise inexplicable." "The likenesses disguised by unlikenesses, which the comparative anatomist discovers between various organs in the same organism, are worse than meaningless if it be supposed that organisms were severally framed as we now see them; but they fit in quite harmoniously with the belief that each kind of organism is a product of accumulated modifications upon modifications. And the presence, in all kinds of animals and plants, of functionally-useless parts corresponding to parts that are functionally-useful in allied animals and plants, while it is totally incongruous with the belief in a construction of each organism by miraculous interposition, is just what we are led to expect by the belief that organisms have arisen by progression."

IV. Arguments from Distribution.—"Given that pressure which species exercise on one another, in consequence of the universal overfilling of their respective habitats—given the resulting tendency to thrust themselves into one another's areas, and media, and modes of life, along such lines of least resistance as from time to time are found—given besides the changes in modes of life, hence arising, those other changes which physical alterations of habitats necessitate—given the structural modifications directly or indirectly produced in organisms by modified conditions; and the facts of distribution in space and time are accounted for. That divergence and re-divergence of organic forms, which we saw to be shadowed forth by the truths of classification and the truths of embryology, we see to be also shadowed forth by the truths of distribution. If that aptitude to multiply, to spread, to separate, and to differentiate, which the human races have in all times shown, be a tendency common to races in general, as we have ample reason to assume; then there will result those kinds of spacial relations and chronological relations among the species, and genera, and orders, peopling the Earth's surface, which we find exist. The remarkable identities of type discovered between organisms inhabitating one medium, and strangely modified organisms inhabiting another medium, are at the same time rendered comprehensible. And the appearances and disappearances of species which the geological record shows us, as well as the connections between successive groups of species from early eras down to our own, cease to be inexplicable" (Principles of Biology, i. p. 489).

"Thus," Spencer concludes, "of these four groups each furnished several arguments which point to the same conclusion; and the conclusion pointed to by the arguments of any one group, is that pointed to by the arguments of every other group. This coincidence of coincidences would give to the induction a very high degree of probability, even were it not enforced by deduction. But the conclusion deductively reached is in harmony with the inductive conclusion."

CHAPTER XI

AS REGARDS HEREDITY

Problems of Heredity—Physiological Units—A Digression—The Germ-Cells—Transmission of Acquired Characters—Inconceivability—A Priori Argument—Practical Conclusion

Heredity is the relation of genetic continuity which links generation to generation. An inheritance is all that the organism is or has to start with on its life-journey in virtue of the hereditary relation to parents and ancestors. In all ordinary cases, the inheritance has its initial material basis in the egg-cell and the sperm-cell which unite in fertilisation at the beginning of a new life, and these two kinds of germ-cells, which bear the maternal and the paternal contributions, have their peculiar virtue of reproducing like from like, just because they are the unchanged or very slightly changed cell-descendants of the fertilised ova from which the parents arose. A bud or a cutting separated off from a living creature—tiger-lily or potato, polyp or worm—reproduces an entire organism like the parent, if the appropriate nurture-conditions are available; and it can do so because it is a fair sample of the parental organisation. Similarly a germ-cell or two germ-cells in conjunction can develop into a creature like the parent or parents, in virtue of being the condensed essence of the parental organisation. And the germ-cell is this because of its direct continuity through undifferentiating cell-divisions with the original germ-cell from which the parental body developed.

Even in ancient times men pondered over the resemblances and differences between children and their parents—for like only tends to beget like—and wondered as to the nature of the bond which links generation to generation. But although the problems are old, the precise study of them is altogether modern. The first great step towards clearness was the formulation of the cell-theory by Schwann and Schleiden (1838-9), by Goodsir and Virchow, which made it clear that all but the simplest organisms are built up of cells or modifications of cells, and that the individual life usually begins as a fertilised egg-cell which proceeds by division and re-division, by differentiation and integration, to develop a more or less complex "body." It has become gradually clear that while the fertilised egg-cell gives rise to body-cells which become specialised, it also gives rise to unspecialised descendant-cells, which take no share in body-making, but become the germ-cells—the potential starting-points of another generation. A second great step was the accumulation of facts of inheritance showing that all sorts of qualities innate or inborn in the parents, essential and trivial, normal and abnormal, bodily and mental, may be transmitted to the offspring as part of the organic heritage. A third great step was implied in the acceptance which Darwin in particular won for the general idea of descent, for it is hardly too much to say that the scientific study of the problems of heredity began when it was recognised that heredity is a fundamental condition of evolution.

Problems of Heredity.—In regard to Heredity there are three large problems which tower above the crowd of more detailed problems. The first is: In what way are the germ-cells peculiar, how do they differ from ordinary cells, what gives them their unique reproductive power, how do they come to be such marvellous units that their development results in a new organism? Only two answers have been suggested: (1) that the germ-cells become receptacles of representative samples from the different parts of the body (the pangenetic theory), and (2) that the germ-cells owe their unique character to the fact that they are, along lines of undifferentiated cell-lineage, the direct descendants of the fertilised ova of the parents (the theory of germinal continuity). Thanks, largely, to Weismann, the second view has prevailed over the first, for which there is little factual basis.

The second large problem is as to the way in which it may be supposed that the hereditary qualities are represented in the germ-cell. Is the germ-cell an extremely complex chemical mixture without pre-formed architecture, which, as it lives and grows, gradually gives rise to heterogeneous elements, differentiating along diverse lines according to their diverse relations to one another and to their surrounding conditions? Or is it from the first a complex architecture, an intricate organisation of a large number of items representing particular qualities, a mosaic of inheritance-bearers?

The third large problem is as to the modes in which the inheritance, normally bi-parental, and in some sense always a mingling of ancestral contributions, can express itself. Sometimes the expression is one-sided, sometimes it is a blend. The mother may look out of one eye, and the father out of another, or the grandfather may be re-incarnated. By inter-breeding hybrids pure types may be got, or reversions, or "an epidemic of variations." This is the problem of the diverse modes of hereditary transmission, which we know in some cases to be expressible in a formula, such as Mendel's law or Galton's law, and for which we can sometimes hazard a hypothetical physiological interpretation.

Physiological Units.—To each of these three problems Spencer made a contribution. He started with the legitimate and fertile hypothesis of "physiological units"—the ultimate life-bearing elements, intermediate between the chemical molecules and the cell. Just as the same kinds and even the same number of atoms compose by different arrangements numerous quite different chemical molecules, e.g. in the protein-group, so out of similar molecules diversely grouped an immense variety of "physiological units" may be evolved. Out of the same pieces of coloured glass one may get in the kaleidoscope a very large number of distinct patterns, so in the course of nature similar molecules, grouping themselves differently, have formed a very large number of distinct "physiological units." The grouping is not merely positional and static as in the kaleidoscope; it is dynamic and vital. Since Spencer sketched his idea in 1864 many biologists have thought of units intermediate between the chemical molecules and the cell, and the number of different names which have been bestowed upon them is extraordinary, each voyager re-naming his discovery, ignorant of or ignoring those who had previously sailed the same seas. This recognition of "physiological units" was a natural step in analysis as soon as it began to be recognised that the cell was a little world in itself, a "firm" with many partners. While we cannot agree with Delage that "Spencer est le vrai père de la conception initiale," since Brücke expressed the same idea in 1861, Spencer's exposition in 1864 was quite independent, and it has not found the recognition it deserved.

It should be noted that the "gemmules" which Darwin assumed in his provisional hypothesis of pangenesis to be given off by the various cells of the body, were supposed to be of innumerable unlike kinds, whereas in Spencer's argument "the implication everywhere is that the physiological units are all of one kind."

It is admitted that the molecules of a crystallisable substance have more or less mysterious relations to one another—"polarities" as we call them—which result in definite crystalline forms appearing in definite conditions, with a certain amount of diversity as everyone may see in snow-crystals, and as is more precisely known in the case of certain substances which have several forms of crystallisation. But just as chemical molecules have in virtue of their organisation (always dynamic as well as static) certain prescribed modes of relating themselves to others like themselves, and building up a beautiful integrate, a crystal, so, as Spencer pointed out, the "physiological units" have their "polarities," i.e. their inherent constitutional tendencies to build up forms along with their fellows. Here we have two useful suggestions, (1) that development is like an elaborate organic crystallisation, only much more energetically dynamic, and (2) that the big fact of heredity—that like tends to beget like—has its parallel in the way in which a minute fragment of a crystal can in the appropriate environment of a solution of the same substance build up a crystal like the original form from which it was separated. Germ-cells are potential samples of the organisation which is expressed in the parent, but Spencer did not advance to the more distinctively modern position which recognises that they are separated off rather from the fertilised ovum which gave rise to the parent's body than from that body itself. The parental body is the trustee rather than the producer of the germ-cells.

A Digression.—Here we must digress a little to compare Spencer's conception of physiological or constitutional units with Weismann's conception of the Germ-Plasm. According to Weismann, there is in the nuclei of the germ-cells a distinctive physical basis of inheritance, the germ-plasm. It is the vehicle of the hereditary qualities, the architectural substance which enables the germ-cell to build up an organism; it has an extremely complex and at the same time persistent structure. Following a hypothesis of De Vries, he supposed that the readily stainable nuclear bodies (the chromosomes or idants) consist of a colony of invisible self-propagating vital units or biophors, each of which has the power of expressing in development some particular quality. He supposed that these biophors are aggregated into units of a higher order, known as determinants, one for each structure of the body which is capable of independent variation. These determinants are supposed to be grouped together in ids, each of which is supposed to possess a complete complement of the specific characters of the organism and also to have an individual character. The ids are arranged in linear series to form the visible idants or chromosomes, which will be slightly different from one another according to the individualities of the component ids. When the fertilised egg-cell develops, it gives rise (1) to somatic cells which carry with them part of the germ-plasm, and differentiate to form the body, and (2) to the germ cells which reserve part of the germ-plasm in an unchanged state, and eventually give rise in appropriate conditions to new individuals and their germ-cells.

Spencer refused to accept the contrast between body-cells and germ-cells as expressing a fact, and referred for his reasons to the numerous cases in which small pieces of a plant or polyp may grow into an entire organism. But when he represented Weismann as maintaining that the "soma contains in its components none of those latent powers possessed by those of the germ-plasm," he did not do justice to the comprehensive theory of the "Germ-plasm." For Weismann assumes that in certain cases the body-cells, even though differentiated, may carry with them some residual unused-up germ-plasm.

When a lizard regrows a lost tail—effectively responding to a casualty which has been common for untold generations—Weismann interprets the mechanism of this as due to a reserve of tail-determinants resident at or near the place of breakage, and localised there as the result of a long-continued process of selection. A chamæleon does not regenerate its tail, and this may be interpreted in terms of the selection-theory, since the chamæleon with its tail coiled up or embracing a branch has not been, in the course of its evolution, subjected to the frequently recurrent casualty which has beset most other lizards. Spencer said, "We cannot arbitrarily assume that wherever a missing organ has to be reproduced there exists the needful supply of determinants representing that organ," but Weismann made no such arbitrary assumption. Many organs are lost which are not regenerated, even when, as far as materials or differentiation are concerned, it would be easy to replace them. Why the everywhere present uniform physiological units that Spencer believed in should not replace them, we do not know; but if the distribution of regenerative determinants has been wrought out by selection, we understand the facts.

Spencer said that the hypothesis of a supply of determinants lying latent at or near the seat of injury, and able to reproduce the missing part in all its details, and to do this several times over, was "a strong supposition." We venture to think that the hypothesis that the same result is achieved by the "physiological units," which are all of the same kind, is a weak supposition. Spencer said: "Reproduction of the lost part would seem to be a normal result of the proclivity towards the form of the entire organism." But it is difficult to see why "proclivity of the physiological units towards the form of the entire organism" should bring about the regeneration of a tail here and a head there, a claw here and an eye there. But Spencer was too acute a thinker not to feel that if the theory of regenerative determinants was "incompetent," his own theory, which interpreted regeneration as due to the activity of physiological units, "with a proclivity towards the organic form of the species," did not cover the facts; e.g. the establishment of "false-joints," where the ends of a broken bone failing to unite remain movable one upon the other. Therefore he suggested a qualification of his hypothesis.

In "the social organism," it is often seen that the components of an aggregate "have their activities and arrangements mainly settled by local conditions." "A local group of units, determined by circumstances towards a certain structure, coerces its individual units into that structure." In an emigrant settlement, "individuals are led into occupations and official posts, often quite new to them, by the wants of those around—are now influenced and now coerced into social arrangements which, as shown perhaps by gambling saloons, by shootings at sight, and by lynchings, are scarcely at all affected by the central government. Now the physiological units in each species appear to have a similar combination of capacities. Besides their general proclivity towards specific organisation, they show us abilities to organise themselves locally; and these abilities are in some cases displayed in defiance of the general control, as in the supernumerary finger or the false joint. Apparently each physiological unit, while having in a manner the whole organism as the structure which, along with the rest, it tends to form, has also an aptitude to take part in forming any local structure, and to assume its place in that structure under the influence of adjacent physiological units" (Principles of Biology, revised edition, i. p. 364).

The experiments of Born and others have shown that fragments of a young tadpole may go on developing to some extent after they are cut off, and that the undifferentiated rudiment of a limb may be successfully grafted on to another tadpole. "In brief, we may say that each part is in chief measure autogenous." "Though all parts are composed of physiological units of the same nature, yet everywhere, in virtue of local conditions and the influence of its neighbours, each unit joins in forming the particular structure appropriate to its place." This conclusion is very interesting when compared with that reached more inductively by many embryologists (of the so-called epigenetic school), namely, that what a blastomere or cleavage-cell of an egg does, is determined by its intra-embryonic environment, by its relations, both statical and dynamical, to the whole organisation of which it forms a part. As Driesch puts it: "The relative position of a blastomere in the whole determines in general what develops from it; if its position be changed, it gives rise to something different; in other words, its prospective value is a function of its position." But those who assume heterogeneous determinants do not thereby exclude what truth there may be in this view that what an early blastomere does is a function of its inter-relations.

But let us consider how much Spencer puts to the credit of his "constitutional units." (1) They carry within them the traits of the species and even some of the traits of the ancestors of the species, the traits of the parents and even some of the traits of their immediate ancestors, and the congenital idiosyncrasies of the individual itself. In this they resemble the germ-plasm. (2) They "must be at once in some respects fixed and in other respects plastic; while their fundamental traits, expressing the structure of the type, must be unchangeable, their superficial traits must admit of modification without much difficulty; and the modified traits, expressing variations in the parents and immediate ancestors, though unstable, must be considered as capable of becoming stable in course of time." Again they resemble the germ-plasm. (3) Once more, "we have to think of these physiological units (or constitutional units as I would now re-name them) as having such natures that while a minute modification, representing some small change of local structure, is inoperative on the proclivities of the units throughout the rest of the system, it becomes operative in the units which fall into the locality where that change occurs." Here they part company from the germ-plasm, except in so far as it may be said that the development of the distributed determinants is in part dependent on local conditions. (4) Finally, since Spencer supposed "an unceasing circulation of protoplasm throughout an organism," such that "in the course of days, weeks, months, years, each portion of protoplasm visits every part of the body"—a wild assumption—"we must conceive that the complex forces of which each constitutional unit is the centre, and by which it acts on other units while it is acted on by them, tend continually to re-mould each unit into congruity with the structures around: superposing on it modifications answering to the modifications which have arisen in these structures. Whence is to be drawn the corollary that in the course of time all the circulating units—physiological, or constitutional if we prefer so to call them—visit all parts of the organism; are severally bearers of traits expressing local modifications; and that those units which are eventually gathered into sperm-cells and germ-cells also bear these superposed traits."

This theory—which is not unlike a combination of Darwin's pangenesis with De Vries's neo-pangenesis—is very significant, for it discloses Spencer's hypothesis as to the modus operandi of the transmission of acquired characters. But there is unfortunately no factual warrant for the assumption that the constitutional units visit one another in various corners of the body, getting impressions as they go, or for the assumption that they are eventually gathered into the germ-cells—an assumption which shows how far Spencer deliberately stood from the conception of the continuity of the germ-plasm. Even if we suppose an organism to undergo numerous modifications in different parts of its body, as a plant may do when it is transferred from the Alps to the lowlands; even if we suppose the constitutional units—which are all of one kind—to circulate and become bearers of the traits expressing local modifications, we have to face other questions: do they all become remoulded in relation to all the modifications? or do some become remoulded in relation to one modification and some in relation to another? or do all the modifications so hang together that one kind of alteration impressed upon the constitutional units covers them all? The difficulties of the conception of constitutional-units certainly do not seem less than the difficulties of the conception of specific determinants.

Even to the general reader, who is not concerned with the problem of the mechanism of inheritance and development, who has a shrewd suspicion that it is one of those things no fellow can understand, our digression should be interesting, for it illustrates Spencer's fertility of invention and his adroitness in lugging in one hypothesis after another to eke out a theory which in its first statement appears to be very simple. It is instructive to observe how the constitutional units at first so harmlessly simple, grow under the conjurer's hands until they become more marvellous than Clerk Maxwell's "sorting demons."

But it is more instructive still to hear the conclusion of the whole matter. "At last then we are obliged to admit that the actual organising process transcends conception. It is not enough to say that we cannot know it; we must say that we cannot even conceive it. And this is just the conclusion which might have been drawn before contemplating the facts. For if, as we saw in the chapter on "the Dynamic Element in Life," it is impossible for us to understand the nature of this element—if even the ordinary manifestations of it which a living body yields from moment to moment are at bottom incomprehensible; then still more incomprehensible must be that astonishing manifestation of it which we have in the initiation and unfolding of a new organism." "Thus all we can do is to find some way of symbolising the process so as to enable us most conveniently to generalise its phenomena; and the only reason for adopting the hypothesis is that it best serves this purpose."

But the hypothesis only serves the purpose because the constitutional units are gradually invested with the powers of effective response, co-ordination, and the like which remain the secret of the organism as a whole—the secret of life, which many think will never be read until we recognise that it is also the secret of mind.

The Germ-Cells.—According to Spencer, "sperm-cells and germ-cells are essentially nothing more than vehicles in which are contained small groups of the physiological units in a fit state for obeying their proclivity towards the structural arrangement of the species they belong to," and "if the likeness of offspring to parents is thus determined, it becomes manifest, a priori, that besides the transmission of generic and specific peculiarities, there will be a transmission of those individual peculiarities which, arising without assignable causes, are classed as spontaneous." Not only are the main characters transmitted, the same may be true of even minute details—varietal characters, like the taillessness of Manx cats, and individual congenital peculiarities such as a sixth finger; normal qualities such as swiftness in race-horses, abnormal qualities such as nervousness in man. Here Spencer was of course at one with all biologists.

Transmission of Acquired Characters.—He went on, however, to try to substantiate the proposition, which has been the subject of so much discussion, that modifications or acquired bodily characters are also transmissible, and we must follow his argument carefully.

He first points out that when a structure is altered by a change of function the modification is often unobtrusive, and its transmission consequently difficult to detect. "Moreover, such specialities of structure as are due to specialities of function, are usually entangled with specialities which are, or may be, due to selection, natural or artificial. In most cases it is impossible to say that a structural peculiarity which seems to have arisen in offspring from a functional peculiarity in a parent, is wholly independent of some congenital peculiarity of structure in the parent, whence this functional peculiarity arose. We are restricted to cases with which natural or artificial selection can have had nothing to do, and such cases are difficult to find. Some, however, may be noted."

When a plant is transferred from one soil to another it undergoes "a change of habit"; its leaves may become hairy, its stem woody, its branches drooping. "These are modifications of structure consequent on modifications of function that have been produced by modifications in the actions of external forces. And as these modifications reappear in succeeding generations, we have, in them, examples of functionally-established variations that are hereditarily transmitted." But this is a non sequitur, since the modifications may reappear merely because they are re-impressed directly on each successive generation.

Spencer notes that in the domestic duck the bones of the wing weigh less and the bones of the leg more in proportion to the whole skeleton than do the same bones in the wild duck; that in cows and goats which are habitually milked the udders are large; that moles and many cave-animals have rudimentary eyes, and so on. But all these results may be readily interpreted as due to selection of germinal variations.

The best examples of inherited modifications occur, he says, in mankind. "Thus in the United States the descendants of the immigrant Irish lose their Celtic aspect, and become Americanised.... To say that 'spontaneous variation' increased by natural selection can have produced this effect is going too far." But if the vague statement as to the Americanisation of the Irishman be correct, and if it be true that intermarriage is rare, it remains probable that the Americanisation is a modificational veneer impressed afresh on each successive generation.

"That large hands are inherited by those whose ancestors led laborious lives, and that those descended from ancestors unused to manual labour commonly have small hands, are established opinions." But if we accept the fact, it is easy to interpret the size of the hands as a stock-character correlated with a muscularity and vigour, and established by selection. The prevalence of short-sightedness among the "notoriously studious" Germans is a singularly unfortunate instance to give in support of the inheritance of functional modifications, for there is no reason to believe that short-sightedness is primarily an acquired character. Nor is it confined to readers.

Spencer twits those who are sceptical as to the transmission of acquired modifications, for assigning the most flimsy reasons for rejecting a conclusion they are averse to; but when Spencer cites the inheritance of musical talent and a liability to consumption as evidence of the transmission of functional modifications, we are reminded of the pot calling the kettle black.

Spencer made his position stronger by adducing what he calls negative evidence, namely those "cases in which traits otherwise inexplicable are explained if the structural effects of use and disuse are transmitted."

(1) First he refers to the co-adaptation of co-operative parts. With the enormous antlers of a stag there is associated a large number of co-adaptations of different parts of the body, and similarly with the giraffe's long neck and the kangaroo's power of leaping. Spencer argued that the co-adaptation of numerous parts cannot have been effected by natural selection, but might be effected by the hereditary accumulation of the results of use. The difficulty is to discover how much deep-seated co-adjustment can be effected by exercise even in the course of a long time, and the theory requires such data before it can be more than a plausible interpretation, with certain a priori difficulties against it. If an animal suddenly takes to leaping many individual adjustments to the new exercise will arise; if the animals of successive generations leap yet more freely, they will individually acquire more thorough adjustments up to a certain limit; meanwhile there may arise constitutional variations making towards adaptation to the new habit, and under the screen of the individual modifications these may increase from minute beginnings till they acquire selection-value. Professors Mark Baldwin, Lloyd Morgan, and Osborn, have all made the same useful suggestion that adaptive modifications acquired individually may act as the fostering nurses of constitutional variations in the same direction until these coincident variations are large enough in amount to be themselves effective.

(2) Secondly, Spencer dwelt upon the notably unlike powers of tactile discrimination possessed by the human skin, and sought to show that while these could not be interpreted on the hypothesis of natural selection or on the correlated hypothesis of panmixia, they could be interpreted readily if the effects of use are inherited. But the difficulty again is to get secure data. It is uncertain how much of the inequality in tactile sensitiveness is due to individual exercise and experience, though it is certain that tactility in little-used parts can be greatly increased by use. Nor is it certain how much of the apparent unlikeness in tactility is due to unequal distribution of peripheral nerve-endings and how much to specialised application of the power of central perception. As Prof. Lloyd Morgan says: "We do not yet know the limits within which education and practice may refine the application of central powers of discrimination within little-used areas. The facts which Mr Spencer adduces may be in large degree due to individual experience; discrimination being continually exercised in the tongue and finger-tips, but seldom on the back or breast. We need a broader basis of assured fact." Nor, it may be added, is the action of selection to be excluded.

(3) Spencer's third set of negative evidences was based on rudimentary organs which, like the hind limbs of the whale, have nearly disappeared. Dwindling by natural selection is here out of the question; and dwindling by panmixia, i.e. the diminution of a structure when natural selection ceases to affect its degree of development, "would be incredible, even were the assumptions of the theory valid." But as a sequence of disuse the change is clearly explained. Prof. Lloyd Morgan replies: "Is there any evidence that a structure really dwindles through disuse in the course of individual life? Let us be sure of this before we accept the argument that vestigial organs afford evidence that this supposed dwindling is inherited. The assertion may be hazarded that, in the individual life, what the evidence shows is that, without due use, an organ does not reach its full functional or structural development. If this be so, the question follows: How is the mere absence of full development in the individual converted through heredity into a positive dwindling of the organ in question?" Moreover, the convinced Neo-Darwinian is not in the least prepared to abandon the theory of dwindling in the course of panmixia, especially in the light which Weismann's conception of Germinal Selection has thrown on this process.

The inductive evidence in support of the conclusion that bodily modifications due to use or disuse or environmental influence can be as such or in any representative degree transmitted, is very weak. The so-called evidences are often anecdotal and vague, often irrelevant and fallacious, and those Spencer adduced are by no means convincing. Let us consider the question briefly from the a priori side.

The general argument against the hypothesis rests on a realisation of the continuity of the germ-plasm. For if the germ-plasm, or the material basis of inheritance within the germ-cells, be somewhat apart from the general life of the body, often segregated at an early stage, and in any case not directly sharing in the every day metabolism, then there is a presumption against the likelihood of its being readily affected in a specific manner by changes in the nature of the body-cells. The germ-cell is in a sense so apart that it is difficult to conceive of the mechanism by which it might be influenced in a specific or representative manner by changes in the cells of the body.

On the other hand, in many plants and lower animals, the distinction between body-cells and germ-cells is far from being demonstrably marked, and even in higher animals we cannot think of the germ-cells as if they led a charmed life uninfluenced by any of the accidents and incidents in the daily life of the body which is their nurse, though not exactly their parent. No one believes this, Weismann least of all, for he finds one of the chief sources of germinal variation in the nutritive stimuli exerted on the germ-plasm by the varying state of the body. The organism is a unity; the blood and lymph and other body-fluids form a common internal medium; various poisons may affect the whole system, germ-cells included; and there are real though dimly understood correlations between the reproductive system and the rest of the organism.

There are some who pretend to find in this admission "a concealed abandonment of the central position of Weismann," for if, they say, the germ-plasm is affected by changes in nutrition in the body, and if acquired characters affect changes in nutrition, then "acquired characters or their consequences will be inherited." But it is a quite illegitimate confusion of the issue to slump acquired characters and their consequences as if the distinction was immaterial. The illustrious author of the Germ-Plasm has made it quite clear that there is a great difference between admitting that the germ-plasm has no charmed life, insulated from bodily influences, and admitting the transmissibility of a particular acquired character, even in the faintest degree. The whole point is this: Does a change in the body, induced by use or disuse or by a change in surroundings, influence the germ-plasm in such a specific or representative way that the offspring will exhibit the same modification which the parent acquired, or even a tendency towards it? Even when we fully recognise the unity of the organism, or recognise it as fully as we know how, it is difficult to suggest any modus operandi whereby a particular modification in, say, the brain or the thumb can specifically affect the germinal material in such a way that the modification or a tendency towards it becomes part of the inheritance. Did we accept Darwin's provisional hypothesis of pangenesis according to which the parts of the body give off gemmules which are carried as samples to the germ-cells, the possibility of transfer might seem more intelligible. But Darwin's suggestion remains a pure hypothesis, and is admitted by none except in extremely modified form. In fairness, however, we must note how little we understand of the modus operandi of influences which certainly pass in the other direction, from the reproductive organs to the body; we must recall Prof. Lloyd Morgan's warning that although we cannot conceive how a modification might as such saturate from body to germ-cells, this does not exclude the possibility that it may actually do so.

As a matter of fact, Spencer has himself suggested a modus operandi—as already outlined. The constitutional units are supposed to circulate; when they come to a modified organ and visit its modified constitutional units, they are supposed to be themselves impressed; they are supposed to be "eventually gathered into sperm-cells and germ-cells," which thus come to bear the "superposed traits" resulting from modification. But, as we have seen, the difficulty is to find any basis in fact on which these assumptions can rest. Indeed, they are contradictory to well-established physiological facts.

Inconceivability.—In reference to the difficulties which beset theories of heredity, Spencer remarks:—

"If it is said that the mode in which functionally-wrought changes, especially in small parts, so affect the reproductive elements as to repeat themselves in offspring, cannot be imagined—if it be held inconceivable that those minute changes in the organ of vision which cause myopia can be transmitted through the appropriately modified sperm-cells or germ-cells; then the reply is that the opposed hypothesis presents a corresponding inconceivability. Grant that the habit of a pointer was produced by selection of those in which an appropriate variation in the nervous system had occurred; it is impossible to imagine how a slightly different arrangement of a few nerve-cells and fibres could be conveyed by a spermatozoon. So too it is impossible to imagine how in a spermatozoon there can be conveyed the 480,000 independent variables required for the construction of a single peacock's feather, each having a proclivity towards its proper place. Clearly the ultimate process by which inheritance is effected in either case passes comprehension; and in this respect neither hypothesis has an advantage over the other."

Let us consider what Spencer has said in regard to "inconceivability." Most ova are very minute cells, often microscopically minute, and a spermatozoon may be only 1/100,000th of the ovum's size—inconceivably minute, but yet exceedingly real and potent. We cannot conceive how a complex inheritance made up of numerous contributions is potentially contained in such small compass, and yet in some form it must be. Similarly, we cannot conceive how the pin-head like brain of the ant contains all the ant's "wisdom."

Those who find it difficult to believe that items so minute as the germ-cells can have room for the complexity of hereditary organisation which seems to be a necessary postulate may be reminded of three things: (1) They should recall what students of physics have told us in regard to the fineness, or, from another point of view, the coarse-grainedness of matter. They tell us that the picture of a Great Eastern filled with framework as intricate as that of the daintiest watches does not exaggerate the possibilities of molecular complexity in a spermatozoon, whose actual size is usually very much less than the smallest dot on the watch's face.

(2) It should be remembered that in development one step conditions the next, and one structure grows out of another, so that there is no need to think of the microscopic germ-cells as stocked with more than initiatives. (3) It should be remembered that every development implies an interaction between the growing organism and a complex environment without which the inheritance would remain unexpressed, and that the full-grown organism includes much that was not as such inherited, but has been individually acquired as the result of nurture or external influence.

Now, returning to Spencer, we find that by an extraordinary argument he concludes that the number of determinants required for the development of a single feather in the peacock's tail must be 480,000, and he points to the inconceivability of these being contained, along with much else of course, in the spermatozoon. We are not at present concerned with the precise number of determinants, but we can see no reason why a spermatozoon should not contain millions if they were needed. The inconceivability is a general one; it is due to the difficulty of imaging the complexity of matter.

But the inconceivability of a particular modification of the nose affecting the germ-cells in a specific and representative way is a different kind of inconceivability. It is due to our being unable to imagine any reasonable modus operandi consistent with our knowledge of the structure and metabolism of the organism. As we have seen and emphasised Spencer does himself suggest a modus operandi, but it seems to us to make unwarranted assumptions, and is for that reason to us "inconceivable."

A Priori Argument.—But Spencer advanced an a priori argument to strengthen the position which he felt bound to hold—the transmissibility of acquired characters. "That changes of structure caused by changes of action must be transmitted, however obscurely, appears to be a deduction from first principles—or if not a specific deduction, still, a general implication. For if an organism A, has, by any peculiar habit or condition of life, been modified into the form A', it follows that all the functions of A', reproductive function included, must be in some degree different from the functions of A." [This, we venture to think, must depend on the nature and amount of the modification.] "An organism being a combination of rhythmically-acting parts in moving equilibrium, the action and structure of any one part cannot be altered without causing alterations of action and structure in all the rest." [The appreciability of the change will depend on the amount and nature of the modification, and on the intimacy of the correlation subsisting in the organism. Dislodging a rock may alter the centre of gravity of the earth, but it does not do so appreciably.] "And if the organism A, when changed to A', must be changed in all its functions; then the offspring of A' cannot be the same as they would have been had it retained the form A." [Assuming that is to say that the change in the physiological units of the body affects the physiological units in the germ-cells.] "That the change in the offspring must, other things equal, be in the same direction as the change in the parent, appears implied by the fact that the change propagated throughout the parental system is a change towards a new state of equilibrium—a change tending to bring the actions of all organs, reproductive included, into harmony with these new actions." [It seems to us to pass the wit of man to conceive how or why an improved equilibrium in the use of the hand should involve any corresponding or representative change of equilibrium in the germ-cells.]

Spencer seems to have seen the matter quite clearly. If the physiological units in the germ-cell mould the aggregate organism, the organism modified by incident actions will impress some corresponding modifications on the structures and polarities of its units. And if the physiological units are in any degree so remoulded as to bring their polar forces towards equilibrium with the forces of the modified aggregate, then, when separated in the shape of reproductive centres, these units will tend to build themselves up into an aggregate modified in the same direction.

The drawback to abstract biology based on first principles is that it enables its devotee to develop arguments which seem plausible until they are reduced to the concrete. Why had Herbert Spencer small hands? Because his grandfather and father were schoolmasters who did little from day to day but wield the pen and sharpen the pencil! Through disuse of the sword and the spade their hands were directly equilibrated towards smallness. But since Mr Spencer senior, was "a combination of rhythmically-acting parts in moving equilibrium," the dwindling of the hands and the moulding of the physiological units thereof reverberated through the whole aggregate; a change towards a new state of equilibrium "was propagated throughout the parental system—a change tending to bring the actions of all organs, reproductive included, into harmony with these new actions," or inactions. The modified aggregate impressed some corresponding modification on the structures and polarities of the germ-units. And this was why Herbert Spencer had small hands. At least so he tells us, for the instance is his own.

Practical Conclusion.—It is obvious that we have not in these pages attempted to give an adequate discussion of an extremely difficult problem. We have endeavoured to give a fair statement of Spencer's position in regard to a question which appeared to him of "transcendent importance." "A right answer to the question whether acquired characters are or are not inherited, underlies right beliefs, not only in Biology and Psychology, but also in Education, Ethics, and Politics." "A grave responsibility rests on biologists in respect of the general question; since wrong answers lead, among other effects, to wrong beliefs about social affairs and to disastrous social actions."

It cannot be an easy question this, when we find Spencer on one side and Weismann on the other, Haeckel on one side and Ray Lankester on the other, Turner on one side and His on the other. Therefore while it seems to us that the transmission of acquired characters as strictly defined is non-proven, and while there seems to us to be a strong presumption that they are not transmitted, the scientific position should remain one of active scepticism—leading on to experiment.

And if there is little scientific warrant for our being other than sceptical at present as to the transmission of acquired characters, this scepticism lends greater importance than ever, on the one hand, to a good "nature," to secure which is the business of careful mating; and, on the other hand, to a good "nurture," to secure which for our children is one of our most obvious duties, the hopefulness of the task resting upon the fact that, unlike the beasts that perish, man has a lasting external heritage, capable of endless modification for the better, a heritage of ideas and ideals embodied in prose and verse, in statue and painting, in Cathedral and University, in tradition and convention, and above all in society itself.