oj ! CD -D a O a m a THE SYSTEM OF ANIMATE NATURE THE GIFFORD LECTURES DELIVERED IN THE UNIVERSITY OF ST. ANDREWS IN THE YEARS 1915 AND 1916 BY J. ARTHUR THOMSON, M.A., LL.D. Professor of Natural History in the University of Aberdeen IN TWO VOLUMES VOL. II LONDON WILLIAMS & NORGATE 1920 PRINTED IN U.S.A. . Discontinuous }'ar;ations (or Mutations} and Continuous }'ariations (or Fluctuations). 4. Problem of the Origin of }'ariations. <">. Correlation of Variations. tf. Theori/ of Temporal \'ariations. 7. Ki'idene-es of Definite- nesf in Variability. S (>\ rin-eells on Implicit Organisms. I. The Central rroblem of Etiology If tlie Origin of Heritable Variations, WHU.K tlu' iiviUM-:il uh':i of evolution is :u\vptiil by prao- tic'alh all liviiii:' naturalists, thoiv is iiTeat uncertainty in ~ > regard to the taetors that have been operative in the pi\v. ss. Tlu^ uncertainty is partly due to the difficulty of arirniiii: from a meagre experienee of the present to a past of many millicnis of vears. anol nartlv to the faet that scientific ivtiol- t OJTV is still verv vounii. for it mav almost be said to date from * i *. %' Oarwin's Origin of Species ^iSo^). There art' two main problems of evolution. The tirst asks how we are to aeeonnt for the continual emergence of new things, of changes or variations whieh make an organism appreeiablv ditYerent from its parents or from the rest of its kin. The seeond asks what direetive faetors operate on tlu> variations whieh arise, determining their elimination or their persistence as the ease may be. and working, it may be. towards the familiar but pu.vliiii: result- -the existence of I V 407 408 ORIGINATIVE FACTORS IN EVOLUTION: distinct and relatively well-adapted species. The first ques- tion has to do with primary or originative factors ; the second has to do with secondary or directive factors. It may well be, however, that the discontinuity of species depends more on originative than on directive factors. A good many years ago there was born in a normal North of Scotland family a child who grew up to be a wise and well-proportioned dwarf. He married and had children a certain number of whom were dwarfs. The peculiarity re-appeared in grandchildren and great-grandchildren, and one of the fourth generation was recently at the head of a successful business a wise and well-proportioned dwarf. The question before us, discussible if not answerable, is, What conditioned the dwarf ? This is the fundamental prob- lem of the origin of the distinctively new. Whether it be a clever dwarf, a mathematical genius, a 10-foot tailed cock, a copper-beech, a Greater Celandine with laciniate leaves, the general problem is the same, the old problem of new departures. What are the originative factors in organic evolution ? 2. Variations Distinguished from Modifications. A problem so difficult demands cautious handling. The first question is as to the nature of the novelties that actually occur ; and the sound procedure is to take stock of all observed peculiarities or differences marking off individual organisms of the same kind. These " observed differences ' must be measured and registered without theory or prejudice. We compare the colour of the trout we catch from different streams, the various numerical relations of radial canals and sense-organs in a thousand jellyfishes of the same species, the plumage in a score of ruffs, the number of vertebrae in VARIATION 409 a hundred herrings, and so on. We register these observed differences. It soon becomes plain, however, that analysis of our data is necessary, if we are to avoid fallacy. We must try to sift out peculiarities which are associated with age and with sex, or are directly due to peculiarities of nurture. Tt is obvious that immature herrings must be compared with im- mature, and that we must not mix up the ruffs and the reeves, drones and worker-bees. More difficult, however, is it to separate off those peculiarities which can be experimentally shown to be individually acquired modifications, directly due to peculiarities in nurture (whether nutritional, environmen- tal, or functional). Many crabs are profoundly changed by being parasitised by Sacculina and related forms, and a conclusion as to variability in crabs is vitiated by mixing up the parasitised with the normal. An organism dwarfed by lack of food or lack of space for exercise, such as the fresh-water snails studied by Semper and Do Varigny, is in a different category from a normal dwarf appearing in a family with no dwarfs in its recent lineage. The much cut- up leaves of the fresh-water buttercup in the swiftly flowing water, one of the examples Lamarck gave of the direct results of environmental influence, are not to be placed alongside of the laciniate leaves of a variety of the Greater Celandine (Chclidonium majus) which cropped up without warning in 1590 in an apothecary's garden in Heidelberg, and has been breeding true ever since. Darwin called these directly induced, exogenous modi- fications "definite variations" not a fortunate term; they are currently and unhappily called " individually acquired characters"; they are best called " somatic modifications". They may be defined as individual bodily changes directly 410 ORIGINATIVE FACTORS IN EVOLUTION: due to peculiarities in environment, nutrition, and function, which transcend the limits of organic elasticity and persist after the inducing causes have ceased to operate. As there is not at present any convincing proof of the transmissibility of these somatic modifications, either as such, or in any representative degree, they must be left out, in the first instance, in our inquiry into the origin of the distinctively new. They may be of great import for the individual, a life-saving veneer, but if they are not transmitted they can- not be of more than indirect importance to the race. It does not follow, however, that a changeful environment may not be an originative factor in evolution. When we subtract from the total of observed differences those that can be shown to be modifications, when we also eliminate the peculiarities associated with differences of age and sex, the remainder are for the most part (in proportion to the success of our subtraction) what are called variations inborn not acquired, intrinsic not extrinsic, blastogenic not somatogenic, endogenous not exogenous, arising from the constitution of the germ-cell not impressed from without, expressions not indents. Some of them at least are very transmissible, and it may be said that these constitute the raw materials of evolution. 3. Discontinuous Variations (or Mutations) and Continuous Variations (or Fluctuations). The next step is to inquire whether all the inborn varia- tions are on the same platform, and here we may go back to Darwin's distinction between (a) " single variations ' and (b) " individual variations ", though the terms are not felicitous. (a) By " single variations' Darwin meant sports, abrupt changes, sometimes of notable amount, such VARIATION 411 as that which gave rise to the copper-heech in the 16th cen- tury, or to hornless cattle, or to short-legged sheep, or to Angora rabbits, or to fantail pigeons. They correspond to Galton's " transilient variations ", to Bateson's " discontinu- ous variations ", to De Vries's " mutations ", and the last name should be kept for them. The contrast, it should be noted, is not so much in the amount as in the kind of change. A white rat does not seem to lack very much to make it a brown rat the species whence it sprang, but it was in its day a qualitative new departure, and it has bred true, (b) By " individual variations ' Darwin meant the minute, ubiquitous peculiarities which distinguish child from parent, brother from brother, cousin from cousin. Though he was much interested in the " single variations ' or brusque " sports ", it was in " individual variations ' or minute fluctuations that he found most of the raw materials of new species. " The more I work," he said, " the more I feel convinced it is by the accumulation of such extremely slight variations that new species arise." Some authors have tried to identify Darwin's slight in- dividual variations or fluctuations with the somatic modi- fications already referred to. While this may be sometimes justified in point of fact, Darwin did not regard minute variations as modificational. This is plain from such a sentence as this: "If, as I must think, external conditions produce little direct effect, what the devil determines each particular variation ? ' Moreover, fluctuations or minute variations often arise among animals whose conditions of life appear to be quite uniform. On the other hand, what Johanssen calls fluctuations in " pure lines ' of beans are probably slight modifications due to differences in nurture. Little is known in regard to the transmissibility of 412 ORIGINATIVE FACTORS IN EVOLUTION: fluctuations or minute variations in the Darwinian sense, but the recent work of Castle (1916), for instance, shows that it is in some cases demonstrable. It is a curious fact that one of the reasons why Darwin attached little importance to sports or mutations was his belief that they would be swamped in the inter-crossing. In reality they are highly transmissible. When they come they often come to stay unless they are pathological on the one hand, or too superlative, like geniuses, on the other. What is desirable at present is more evidence of the trans- missibility of the small fluctuations of germinal origin a transmissibility which Darwin assumed without ques- tion. To emphasise the contrast between fluctuating or con- tinuous variations, and saltatory or discontinuous mutations, we may quote a couple of vivid sentences from one of Samuel Butler's Essays. When circumstances are changing, an " organism must act in one or other of these two ways : It must either change slowly and continuously with the surroundings, paying cash for everything, meeting the smallest change with a cor- responding modification so far as is found convenient; or it must put off change as long as possible, and then make larger and more sweeping changes ". " It may be questioned whether what is called a sport is not the organic expression of discontent which has been long felt, but which has not been attended to, nor been met step by step by as much small remedial modification as was found practicable: so that when a change does come it comes by way of revolution. Or, again (only that it comes to much the same thing), a sport may be compared to one of those happy thoughts which sometimes come to us unbidden after VARIATION 413 we have been thinking for a long time what to do, or how to arrange our ideas, and have yet been unable to arrive at any conclusion." To the Dutch botanist De Vries especial credit is due for his recognition of the evolutionary importance of mutations and for his study of their behaviour in inheritance. It is an often told story how he found, in 1886, in a potato- garden near Hilversurn, in Holland, a race of the Evening Primrose ((Enothera lamarckiana) in which the mood was all mutation. In spite of Galton's insistence on the reality of transilient variations and Bateson's marshalling of in- stances of discontinuity, the tendency had grown strong to dogmatise about the continuity of organic change, just as previously about the fixity of species. ' Natura non facit saltus," they said: but De Vries discerned Natura saliatrix in the Evening Primrose of Hilversum, which, by the way, turns out to have been in the 18th century a wild species in North America. Three points may be emphasised. First, that some of the mutants which De Vries's sportive (Enotheras threw off, as an artist might tear sketches from his note-book, were ephemeral failures, while others were viable and bred true, and could not be otherwise described than as species in the making, fingers searching as it were for their appropriate environmental glove. Second, in many cases the mutants were of particular interest because they showed through and through divergences in leaf and stem and flower certainly suggestive of some general disturb- ance of germinal organisation. Just as if the (Enothera was born again ! Third, that the creativeness or sportiveness of the Evening Primrose is not restricted to De Vries's partic- ular race of CEnoihcra lamarckiana. It occurs in other species of Evening Primrose, and also in snapdragon and 414 ORIGINATIVE FACTORS IN EVOLUTION: barley, in strawberry and maize, in pomace-fly and potato- beetle, in rat and in Man himself. Mutations may be induced experimentally, as Professor Tower did with his potato- beetles and as Mme. Henri recently did with the bacillus of anthrax; or they may manifest themselves in wild nature as in the black mutants of Peppered Moth and West Indian Sugar-bird. The result may be a plus or a minus, a dominant or a recessive or neither, pathological or normal. The muta- tion may occur after crossing or in a pure race ; it may show itself potentially before, during, or after fertilisation. In short, there is nothing hard and fast about the origin or nature of mutations : their common features are their brusque appearance, their discontinuity with the parent stock, and their capability of being transmitted intact to a certain proportion of the offspring. The work of Dr. R. R. Gates on (Enothera lamarckiana is of capital importance. It had been suggested that this species might be a cultivated hybrid, and that its remarkable muta- tions might be re-combinations of the Mendelian characters of its parents. But it has been shown that (Enothera lamarck- iana was in the 18th century at least a wild North American species. Moreover, the brusque phenomena of mutation occur not only in (E. lamarckiana, but in (E. biennis, (E. grandi flora, and (E. muricata as well. Of particular interest in many of the mutations of (E. lamarckiana is the fact that they affect several different parts of the plant, including foliage, flowers, and habits. The disturbance produced in the germ-plasm must be of a fundamental character, it has manifold outcrops, as is sug- gested by the names of the mutants gigas, lata, nanella, rubricalyx, brevistylis, and so on. How does Dr. Gates interpret the germinal disturbances VARIATION 415 which result in somatic mutations ? " As regards the ulti- mate nature of mutations, we are inclined to look upon them as the result of various types of change in the nucleus: (1) morphological changes (a) in number, (b) in shape and size of the chromosomes, or in the arrangement of their substance; (2) chemical or functional changes in (a) whole chromosomes or (b) portions of particular chromosomes, by which a function may be modified or lost; (3) two simulta- neous mutations may occur through mismating of the chromo- somes in two pairs so that each germ-cell receives both members of one pair ; (4) changes in the mysterious karyo- lymph or gel which forms the groundwork of the nucleus. Such changes may be thought of as alterations in chemical structure or even in polarity, and may also be supposed to extend to the ground substance of the whole cell. But the real nature of all such changes as those last mentioned is at present highly speculative' (1915, p. 303). 4. Problem of the Origin of Variations. Turning now to the problem of the origin of inborn varia- tions, we may usefully distinguish two levels of difficulty. There are variations and variations. There are some novel- ties that imply just a little more or a little less of some quality, a slightly longer tail, a slightly denser blackness, a slightly stronger flight-muscle, a slightly weaker eye; some that involve a disappearance of an entire character, such as hair or horns, tail or pigment; some that may be described as obvious re-arrangements of the characters displayed by the ancestry, as we see in a piebald pony or in a hybrid cock- atoo. Now it does not seem very difficult to imagine the origin of this kind of quantitative variation. Without pin- ning our faith as yet to any very detailed view of the ma- 416 ORIGINATIVE FACTORS IN EVOLUTION: terial basis of inheritance, we may regard it as certain that the chromosomes play an exceedingly important role as ve- hicles of the heritable qualities. We may compare them to a microscopic pack of cards and we know that they are some- times visibly different from one another in the same germ- cell, and that there is an extraordinarily elaborate shuffling of the cards before development begins. In the reduction- process involved in the maturation of almost every animal egg-cell, half of the ovum's pack is thrown away, usually in the first polar body, and comes to nothing. In the matura- tion of the sperm-cell there is also a halving of the pack, but all the reduced units are in this case functional. In fertilisation the two half-packs come together in intimate and orderly union, though without fusion of chromosomes, forming the zygote-nucleus. The opportunities for permuta- tions and combinations of hereditary items, and for the dropping out of one or more altogether, are many and actual. Thus the origin of variations of a quantitative sort does not seem beyond our comprehension, except in the sense that we do not in any way understand the process of cell-division, whether meiotic or reducing division in the maturation of the germ-cells, or the ordinary equational division in other cases. That this is still only nibbling at the problem is evident when we think of meristic variations (in the number of parts, segments, vertebrae, joints, etc.), which Professor Bate- son has usefully distinguished from substantive variations (in the composition of materials). A re-shuffling of the molec- ular cards within the germ-cell might give rise to a new pigment which was continued in subsequent generations as a definite constituent particle (which we have to credit with great capacity for increase) or as a particular chemical VARIATION 417 ' tendency ' of the protoplasm ; but how are we to picture the origin and continuance of meristic variations? A separate consideration may be given to fertilisation as a source of variation, a view prominent at one stage in the development of Professor Weismann's theories. For a time he was inclined to attach great importance to the mingling (or amphimixis) of two sets of hereditary qualities as a pos- sible source of novelties, but he afterwards attached more importance to the influence that fluctuations in nutrition within the body might have in inducing changes in the germ-plasm or in inducing struggle among the analogous hereditary items. In recent years the Belgian botanist Lotsy has been a thoroughgoing champion of the variational signifi- cance of fertilisation and has gone the length of maintaining that all variation is due to crossing. There is ample experi- mental evidence that novelties may be induced by crossing, and this is not surprising when we remember that two very complex systems, usually of diverse origin, become in fertili- sation a unity that goes on in most cases to develop into a harmonious life. On the other hand, Lotsy's attempt to refer all variations to crossing is extreme. This is shown, for instance, bv the occasional occurrence of variations in u parthenogenetic lineages in which no father intervenes for prolonged periods. Moreover, crossing can be of no avail unless the two sex-cells that combine are different. If they are different it must be by hypothesis because of previ- ous crosses. Thus we simply push the problem back and back to original differences which are left unaccounted for. The problem before which we are baffled is the origin of the distinctively new, where the novelty is qualitative not quantitative. Some would refuse to admit this distinction, 418 ORIGINATIVE FACTORS IN EVOLUTION: and perhaps they are pedantically right: the distinction is one of common sense. There is many a grade between those who find their fingers indispensable in simple computations, and the calculating boy who can tell us in a few seconds the cube root of 2,498,846,293 yet cannot explain how he knows, but there seems good sense in recognising the latter as a qualitative change. So with the mathematical genius, the musical genius, the artistic genius, and there is not any rea- son to believe that Man is the only species that produces geniuses. The evidence of their occurrence elsewhere is in the rapidly-growing records of mutations of large amount. There is a mutation-theory, but is there any theory of muta- tions ? On the dark problem of the origin of the distinctively new some beams of light have been shed. (1) First, there are facts suggesting that deeply saturating environmental influences may act as variational stimuli on the germ-cells and provoke change. Professor MacDougal injected solu- tions of sugar and compounds of calcium, potassium, and zinc into the developing ovaries of one of the Evening Primroses, and got out of several hundreds of seeds sixteen individuals notably atypical, which bred true to the second and third generation. There were not only losses and augmentations, there were well-marked novelties which maintained their distinctiveness when crossed with the parental strains. It should be noted that what Professor MacDougal injected was not very much out of the way, and might be paralleled by nat- ural changes in the chemical composition of the sap of the plant. Professor Punnett expresses the view of many natural- ists when he says : " There is reason to suppose that environ- mental change leads to abnormal divisions in the ripening germ-cells, and that these abnormal divisions are the starting- VARIATION 419 point of the new variety ' (Article Heredity, Hastings' Encyclopaedia of Religion and Ethics). Pointing in the same direction are the well-known experi- ments of Professor Tower, who subjected potato-beetles to un- usual conditions of temperature and humidity when the male and female reproductive organs were at a certain stage of development. The results were strangely lacking in uniform- ity, but some of the offspring showed striking and persistent changes, not only in colour and markings, but also in some details of structure. Professor Tower's work has met with some adverse criticism, but, taken along with similar experi- ments, it suggests that we must not overlook the possibility of deeply-saturating environmental influences acting as varia- tional stimuli, affecting not the body of the parent, but the germ-cells within. Here should be included Weismann's view that fluctuations in bodily nutrition may prompt the germ-plasm to vary. (2) Some of the researches of recent years, such as those of Dr. R. Ruggles Gates on Evening Primroses ((Enothera) and of Prof. T. H. Morgan on the Pomace-fly (Drosophila) have focussed attention on the chromosomes. It is a distinct step to know that certain peculiarities of particular mutants are associated with visible alterations in the chromosomes of the fertilised egg-cell. It is very interesting to know that while the fundamental number of chromosomes for the genus CEnothera is 14, this has become 15 in lata and semi- lata, 21 in semigigas, 28 in gigas, and so on. These are the numbers observed in the fertilised egg-cell and in every ele- ment throughout the plant. In this connection a reference may be made to what obtains in Man. Competent observers have stated that the cells of the male negro have 22 chromosomes, and it is probable 420 ORIGINATIVE FACTORS IN EVOLUTION: that the negress has 24, at least in some cases. Now in the white man and woman the enumerations of Winiwarter and others have usually been 47 and 48. It seems curiously difficult to reach certainty in regard to this simple point, but there is no harm in asking, as Dr. Gates does, whether the white man may not have originated from a black race by a " tetraploid mutation and its consequences ". The nuclear changes studied in CEnothera in their as- sociation with particular mutations are not restricted to changes in the number of chromosomes ; they may concern their shape, size, and structure. What has been gained is a demonstration that in some cases the bodily peculiarities of mutants are correlated with visible changes in germinal organisation. Now one is quite aware that this is just telescoping-down the Proteus of the full-grown organism into the germ-cell phase of its being, and that a recognition of germinal dis- turbances does not tell us what conditions them. As Professor Bateson has often said, we find ourselves confronted with the oppressive difficulty of cell-division and irregularities in its procedure. Yet there is an enlightening gleam in the proof that somatic mutations are correlated with antecedent germinal disturbances, for we know that abnormal cell-divi- sions occur in various conditions in Nature, and we have already referred to the opportunities for re-arrangements that occur in the early history and maturation of the germ- cells. Is there any further light? We must remember that chromosomes are living units in a complex environment, and just as Bacteria sometimes change suddenly in their physiological properties, so chromo- somes may vary in their stereochemic architecture or in functional powers. Moreover, it is not fanciful to suppose VARIATION 421 that these vital units, which have great persistence of ' in- dividuality 7 , may exhibit age-changes or periodic reorganisa- tion processes. Here may be profitably considered the recent work on the Slipper-Animalcule (Paramecium aurelia) by Professor Woodruff and Miss Erdmann. Woodruff has kept a pure line of this Ciliate healthy for over seven years, through more than 4500 generations. As is usual in a pure line all descended from one there was no conjugation. On an av- erage of once a month, however, a remarkable regulatory process occurs, which the authors call endomixis, which secures the indefinite life of the race. Nuclear changes, comparable to those that precede conjugation in normal wild conditions, set in ; the old nuclear material, both macro- nuclear and micronuclear, is disintegrated and re-organised. But there is no formation of stationary and migratory micronuclei as there is before conjugation. For conjugation is not going to occur ; something that takes its place is occur- ring endomixis. ISTow it seems probable that such a periodic re-organisation of nuclear material will afford op- portunity for plasmic re-arrangement, and this may imply the origin of variations even within a pure line. Professor Jennings has found in pure lines of non-conjugating Para- mecium evidence of variations about the mean. These might be due to re-arrangements effected in endomixis. It is conceivable, as Woodward and Erdmann point out, that " heritable 7 variations may result from some rare re- combinations in endomixis. This Paramecium is a very complicated organism, as Prof. Clifford Dobell has vividly emphasised, on the non- cellular line of evolution, and we find it in certain conditions exhibiting a monthly re-organisation as part of its life-cycle. 422 ORIGINATIVE FACTORS IN EVOLUTION: Is it not possible that some similar re-organisation may normally occur in Metazoa at the origin of each individual life, and that, if it does, there is no need to look about for any special cause ? It is all in the day's work, it is part of the programme of the essentially regulative life-cycle. We may recall, too, that variation occasionally occurs in parthenogenetic or aspermic development, as well as in the ordinary process. We are not seeking to l explain ' variations by verbal inventions. Our argument is quite clear: Certain mutations in organisms are preceded by germinal disturbances, perhaps these germinal disturbances are comparable to endomixis in Paramecium. It is always a step towards understanding to put one obscure process alongside of another which is similar to it and which may be more amenable to experi- mental treatment. Therefore we suggest that endomixis may be profitably considered along with the problem of the origin of variations. Another gleam of light may possibly be found in Professor Child's long-continued study of processes of senescence and rejuvenescence, a study recently presented in its entirety in a remarkable volume Senescence and Rejuvenes- cence (1915). Professor Child finds that when a fragment of a Planarian regrows a whole, there is a rejuvenescence dur- ing the re-constitution ; the rate of metabolism is high and the resistance-power is great. The metabolism may be measured by Tashiro's ' biometer ', an extraordinarily delicate reg- ister of the CO 2 output, or more indirectly by the degree of susceptibility and resistance to cyanide poisons and the like. Judged by these tests, the regenerating piece of Plana- rian is younger than it was when it formed part of the parent. It literally renews its youth. Similarly, when a Planarian VARIATION 423 or a Hydroid multiplies asexually, the separated-off piece shows marked rejuvenescence as revealed by the two tests named. Professor Child's thesis is this: As an organism differen- tiates, it ages, for the accumulation of relatively inactive con- stituents in the colloidal cytoplasmic substratum necessarily involves a decrease in the metabolic rate ; but there are coun- teractive processes of reduction, removal, and de-differentia- tion, when the metabolic stream erodes its bed instead of depositing materials. These are marked by acceleration in metabolic rate, and constitute rejuvenescence. " It is cer- tain," Professor Child says, " that the new individuals which arise by division or budding from other individuals or from experimentally isolated pieces are to some extent physiologi- cally younger than the parent individual from which they arose.' The idea of a see-saw between processes of senescence and rejuvenescence finds many illustrations among the lower animals, but what of higher levels? Professor Child finds some interesting evidence that the early developmental stages of a number of animal types, before specialisation of cells sets in, are conspicuously young in the physiological sense. The sre nil-cells themselves are verv stable condensations of he- O i/ reditary items, but in the early development there is a time of re-constitution, of de-differentiation, of relaxation. If there is any soundness in this view, in support of which data are, of course, submitted, we may perhaps recognise another opportunity for variation, namely in the very young embryo, where the alleged rejuvenescence may include possibilities of re-arrangement and, as it were, re-tuning. 424 ORIGINATIVE FACTORS IN EVOLUTION: 5. Correlation of Variations. The tendency of modern research has been to lay emphasis on the idea of hereditary particulateness, that the character- istics of organisms are made up of elementary units, without intergrades, as sharply separated from one another as the chemical elements. This is the idea of " unit characters ", independently heritable, and independently variable. It is very striking that a trivial feature in the hands a reduc- tion of the index and middle finger (in spite of the presence of a little extra triangular bone at their bases), and a con- sequent projection of the ring finger, should behave as a Mendelian character for at least four generations and be found in fifteen out of thirty-six descendants of the family investigated. (See H. Drinkwater, Journ. Anat. Physiol., L., 1916, pp. 177-186, 14 figs.) There is indirect evidence that particular unit characters are represented by particular particles (factors, determinants, or genes) in the germ-plasm, or perhaps by ultra-microscopic differences of architecture, and the idea works well, like the atomic theory in chem- istry. But it has its limitations and it must not be pressed so hard that we lose sight of the unity of the organism even in the germ-cell phase of its being, and of the fruitful con- ception of correlated variations. An exaggeration of the idea of particulateness leads to a view which is too mechan- ical to fit living creatures, as if the organism evolved like a machine perfected piecemeal by the adding on of many little patents independent of each other. A reaction may be seen in the recent book by Prof. T. H. Morgan and others on The Mechanism of Mendelian Inheritance (1915), where it is insisted that the so-called unit character is only the most obvious or most significant product of the postulated VARIATION 425 ' factor ', that the effects of a i factor ' may he far-reaching and manifold, and that a single character may depend on many ' factors ? which interact. " Cases of interaction of factors, in which the effect of one factor is altered by the action of another factor, are very numerous ' (p. 46). " The expression of a factor-difference may not be limited to one region but may produce a different effect in different re- gions." Many considerations suggest that we should do well to ap- preciate afresh the idea which Darwin and Sir Ray Lan- kester have emphasised of the " correlation of variations ", that one change, as we see for instance in disease, may have manifold expression or outcrop in different parts of the body, that the organism may change as a unity in many parts at once. It is not difficult to suppose that a change in the rate of a particular kind of metabolism may reverberate through the body. As Mr. J. T. Cunningham and Professor Dendy have pointed out, an augmentation or a diminution of certain internal secretions or hormones might have multitudinous transforming effects. 6. Theory of Temporal Variations. Another important idea is that of temporal variations, that is to say alterations in the tempo, or rate, or rhythm of metabolic processes, or in the duration of particular phases in the life-cycle. Many changes of great adaptive- ness are probably due to a lengthening out of one chapter and the telescoping of another. In the remarkable regula- tory influence of the internal secretions in backboned an- imals we get a hint as to the way in which changes in ' time 9 might be effected. It is very interesting to compare different life-histories 426 ORIGINATIVE FACTORS IN EVOLUTION: from this point of view. In some, such as May-flies or Ephemerides, the adult life is condensed into a few days or even hours. It may even be lost altogether as in cases of psedogenesis, where there is juvenile reproductivity. On the other hand, when juvenile life is hazardous, it may be, as it were, telescoped down into the egg; thus the young Mound-bird is able to fly on the day on which it is hatched. In other cases, as in the generations of Planarians badly fed, the animal may be born old. Part of the tune may be played very slowly, part very quickly, and another part left out altogether, and a life-history adaptive to particular condi- tions may be the result of selecting out suitable temporal variations. (See in this connection Mitchell, 1912, and Thomson, 1914.) We must not think too exclusively of variations in struc- ture; many variations may affect rate and intensity; many may be differences in stability of constitution, in rapidity of reflexes and cerebral processes, and in the mysterious quality called vigour. Or, penetrating further still, may we not recognise the possibility of a kind of variation which is of more profit than any increase of stature, strength, or speed, than any perfection of armour or weapons, than any subtlety of protective coloration or mimetic resemblance, a kind of variation that expresses itself in a keener endeavour after well-being, a stronger will to live, and a livelier sense of kinship ? 7. Evidences of Definiteness in Variability. For our interpretation of evolution it is important to rec- ognise the growing body of evidence that variation is a much more definite, much less fortuitous, organic change than was formerly supposed. (A) There are many illustrations of VARIATION 427 what is called orthogenesis, or progressive variation along a definite line. The paleontologists in particular have very strong convictions as to reality of this orthogenesis, and as to the absence of arrows shot at a venture. (B) Instances are accumulating of the occurrence of mutations or brusque varia- tions, and if these come they often come to stay. The Black Mutant of the Peppered Moth was rare 60 years ago ; in many places it has now replaced the originative stock. This lessens the element of the casual in organic evolution. It also lessens the need for over-burdening the role of natural selection in sifting out from amid a crowd of random novel- ties, and as an accumulator of minute increments. (C) But along with this there should be considered the idea, that variations are limited in some measure by what has gone before. At the beginning of each individual life there is the fertilised ovum, a viable unity. If a variation occur it is not like to grip unless it be congruent with the germinal organisation already established; it must harmonise, just as an addition to a crystal must, but within a wider range. The character of the building that has been erected determines in some measure the nature of an addition to it. The idea of architecture is of course only one aspect ; the novelty must be congruent with the previously established reaction system and specific metabolism. Out of the same spring we do not get sweet water and bitter. This is an old but important idea ; we find in Aristotle the suggestion that the possible range of the form of an organ is limited to some extent by its existing differentiation. Thus the element of the fortu- itous shrinks still further. It is interesting to find that monsters sometimes result from infelicitous crossings, but perhaps a greater interest attaches to the fact that monsters are rare in Nature, not only in survival, but in occurrence. 428 ORIGINATIVE FACTORS IN EVOLUTION: An illustration of the limiting of changes by pre-existing organisation may be found in a recent paper by Prof. S. J. Hickson (Mem. $ Proc. Manchester Lit. & Phil. Soc., LX., 1916, pp. 1-15), in which he notes that meristic variability in important organs is much greater in radially symmetrical forms than in bilaterally symmetrical forms where a balance must be kept. In reference to the Pennatulacea he shows that variable or plastic characters may become less variable or plastic as a transition is made from radial to bilateral sym- metry, and points out that increasing rigidity of certain characters leads in some cases to the differentiation of the discontinuous groups which are recognised as species. What we would suggest is carrying this idea from the fully-formed organism to the germ-cell organism, and considering substan- tive as well as meristic variations. 8. Germ-cells as Implicit Organisms. Let us sum up. Germinal disturbances or re-arrangements occur and these may find expression in development as varia- tions or mutations of the organism. The question is, What brings about the re-arrangements ? a question to be asked in the light of the fact that, frequent as variations are, hered- itary constancy, or inertia, or persistence of specificity is even more marked. The following suggestions are before us. (1) That germinal disturbances come about in response to subtle environmental stimuli of a novel kind penetrating in from without and affecting cell-division, or the architecture of the chromosomes, or perhaps the " mysterious karyolymph or gel which forms the groundwork of the nucleus v . Along with definable changes in the external environment may be included changes in the somatic fluids which might affect the nutritive or other metabolism of the germ-cells. (2) That VARIATION 429 in the division of the germ-cells before fertilisation, where there has to be a partition of a complex cytoplasmic and chromosomic cargo between two vessels, losses and augmenta- tions and inequalities may be expected in the transhipment. (3) That in fertilisation, with its intimate and orderly union of paternal and maternal contributions (amphimixis), there may be opportunity for new permutations and combina- tions, the result normally being a viable unity of dual origin. (4) That there may be growth-changes, or regulative re- organisation processes, or rejuvenescences in the germ-cells in the course of their history ; and it is possible that there may be something in Weismann's hypothesis of mtra-germinal struggle. We are thus aware of certain originative factors in evolu- tion, which admit of experimental testing, and we should not lose sight of any of them. Each must be pushed as far as it. will go. Recognising this, some will insist that there is no more to be said, but much to be done. We venture to doubt, however, whether this is not making a tyranny of scientific method (which, after all, is very selective and partial) and giving up the right of speculative adventure. As Karl Ernst von Baer, the great Russian embryologist, said : There is observation, but there is also reflection. Those who have devoted much attention to the occurrence of variation, we think for instance of Darwin and Bateson, have given emphatic expression to their sense of the difficulty of accounting for the origin of the new. The fountain of change, whence are its well-springs ? " As to almost all the essential features, whether of cause or mode, by which specific diversity has become what we perceive it to be, we have to confess an ignorance almost total ' (Bateson, 1913, p. 248). But we also notice that some of those who have given much 430 ORIGINATIVE FACTORS IN EVOLUTION: of their life to the study of the phenomena of variation occasionally lapse from the stern path of science, and in face of the difficulty of the problem ask themselves if they are allowing enough for the fact that the organism is alive. Thus we would quote from the recent work of Dr. R. R. Gates on The Mutation Factor in Evolution this inter- esting sentence : " Just as an Alpine climber dangling over a chasm may, by changing his hold, swing himself on to a shelf from which he can make a fresh start in some other direction, so we may think of the organism trying many un- conscious experiments in its offspring, some of which are hurled by the gravitational effect of natural selection into the abyss of extinction while others with a more fortunate turn rest on a ledge of safety whence new essays of variability begin." But Dr. Gates mutationist all too speedily takes the place of Dr. Gates psycho-biologist. After this one exciting glimpse of the organism as climber we are hurried back to the chemical and physical complexity of the protoplasm and its unique irritability and retentiveness. But we are disposed to linger over the idea of the organism as climber, and the organism here means the germ-cell. It is not sug- gested that the germ-cell is dominated by any purpose of getting to the top of anything, or of circumventing any par- ticular difficulty, but rather that there is inseparable from it a restless experimenting in self-expression, bearing the same relation to the insurgent self-assertiveness of the full- grown creature that the tentatives of dreamland bear to the achievements of open-eyed and deliberate endeavour. The position we are suggesting is that the larger muta- tions, the big novelties, are expressions of the whole or- ganism in its germ-cell phase of being, comparable to experi- ments in practical life, solutions of problems in intellectual VARIATION 431 life, or creations in artistic life. These are accomplished, every one knows, by molecular activities in the brain and body, but they are not intelligibly thought of unless we conceive of the organism as a psycho-physical individuality, a mind-body, or body-mind, as we will. Similarly it may be that our conception of germinal variability is falsely abstract unless we recognise that germ-cells are living individualities of great complexity telescoped-down into a one-celled phase of beings, and that they too make essays in self-expression. Mr. E. S. Eussell (1915, p. 430) has suggested that non- adaptive specific differences which make species discontinu- ous may be profitably compared to the differences between related organic compounds, and that they may be due to differences in metabolism or stereochemic architecture which cannot be other than discontinuous. But adaptive specific characters, whether of internal or external reference, may be the result in the long run of some " obscurely psychic capac- ity for active effort ". " The analogies between intelligent and instinctive behaviour on the one hand and the organic processes of active adaptation on the other, as these are ex- pressed in changes of form, are striking and profound." Mr. Russell goes on to say that behaviour and morphogene- sis are probably different manifestations of one and the same fundamental capacity which cannot be formulated ade- quately without using psychical terms. If it be said that this is retrograde science to fall back on psychical formulation because of the baffling difficulty of physiological formulation, and that it is a reversion to the mediaeval solution of the problem of digestion and the like by calling in the aid of Archegaeus and other indwelling spirits. But it may be answered first, that in giving an account of our own behaviour it is not a hypothesis to re- 432 ORIGINATIVE FACTORS IN EVOLUTION: gard psychical factors as verce causce, that somehow or other the psychical factors we are aware of were implicit in the germ-cell whence we sprang, and that therefore it is not a reversion to mediaeval physiology to keep our mind open to the possibility that the origin of the profounder and more vital variations may not be statable without a recognition of the implicit organism of the germ-cell as at once psychical and metabolic. Perhaps we mislead ourselves by repeating too often the elementary commonplace that the Metazoon begins its life as a single cell. It is true enough in a way, but certainly not the whole truth. It is no commonplace cell, the gamete. It is an implicit organism and within it, in some manner that we cannot begin to image, though we crowd it with factors and genes (the modern successors of Darwin's gem- mules and Weismann's determinants), there lies a complex inheritance, unified afresh at the start of each new genera- tion. If an Amoeba has a behaviour, as Professor Jennings seems to have proved, may not the much more richly-en- dowed germ-cell of a fruit-fly be allowed the capacity of putting its house in order ? If the Foraminifer Technitella Ihompsoni picks and chooses the materials of its encasement and builds this with what looks like a dawning art, may not the ovum of an Evening Primrose be allowed some free- dom of internal architecture ? Germ-cells are not corpuscles of undifferentiated protoplasm. They are individualities that live and multiply, that struggle and combine. They are repositories of multiplicate inheritances borne by strangely persistent smaller living units, the chromosomes, which ad- just themselves in the most momentous of organic compro- mises. Is it fanciful to suppose that these gametes, neither simple cells nor portmanteaus of hereditary factors, but VARIATION 433 unified individualities, experiment internally, not fortui- tously but artistically, not at random nor yet inexorably, not purposefully but perhaps purposively, and that they are body-minds or mind-bodies telescoped down ? In certain moods one feels inclined to agree with those who say to-day what Darwin said more than fifty years ago that our ignorance of variation is profound, and who urge the appropriateness of silence. Yet perhaps it is more wholesome for thinkers to have an exposure of the vast un- certainty that surrounds this central problem of biology than to be led astray by those who confidently declare that organic evolution can be mechanically re-described. If the re-descrip- tion is difficult and still impossible when we use full-blooded biological categories, how must it be if matter-and-motion categories are supposed to be the only legitimate ones ? SUMMAEY. The central and most difficult problem of aetiology concerns the origin of the new, that is, of those variations or mutations that form the raw materials of progress or the reverse. From an unbiassed registration of all observed differences between the members of the same species there have to be subtracted all the peculiarities that can be reasonably interpreted as associated with age and sex, or as individually-acquired somatic modifications di- rectly due to peculiarities of nurture, whether environmental, nutri- tional, or functional. As there is no convincing evidence at present that these extrinsic somatic modifications can be transmitted as such, or in any representative degree, they cannot be included, in the first instance at least, among the raw materials of racial evolution. These are discerned when the modifications in question and the peculiarities associated with age and sex are subtracted from the total of observed differences. For this subtraction brings into view the true variations or mutations inborn not acquired, blastogenic not somatogenic, endogenous not exogenous, expressions or outcomes not indents or imprints. Some at least are very transmissible, and these furnish the raw materials of evolution. 434 ORIGINATIVE FACTORS IN EVOLUTION: Among inborn variations it is useful to distinguish between mutations (Galton's " transilient variations", Bateson's "discontinu- ous variations") and small fluctuating variations. The former arise brusquely, with a measure of perfectness from the first, without intergrades, and are markedly transmissible. The latter are of the nature of "a little more or a little less", they show intergrades; their transmissibility has not been much studied, but it has been proved in a few cases. It is also useful to distinguish quantitative variations from defi- nite novelties. The reduction or exaggeration of a quality, the dropping-out of a character altogether, a re-arranged pattern of hereditary items, may be called quantitative, and may be explained as due to permutations and combinations of the determinants or factors of hereditary characters. For such shufflings of the cards ample opportunities are afforded in the course of the maturation of the germ-cells. Another possibility is afforded at the beginning of each individual life, where, in the great majority of cases, two very complex sys- tems of dual origin become a new unity which normally develops into a harmonious organism. Some modern evolutionists attach great importance to crossing as a cause of variations. But the greater difficulty is with the origin of the distinctively new, of what may be called qualitative variations or mutations, (a) It may be that deeply-saturating environmental influences act as variational stimuli on the germ-cells, provoking change, (b) Definite changes in the nuclear bodies or chromosomes of the germ-cell have been proved to be associated with particular mutations in the full- grown organism, and, in addition to the opportunities for ehromo- somic change afforded in the history of the germ-cells before, dur- ing, and after fertilisation it is possible that chromosomes, which are living units, may change suddenly like Bacteria, or may undergo age-changes, or may exhibit periodic re-organisation like slipper- animalcules, or rejuvenescence-changes like those occurring in some cases of regeneration and asexual multiplication. The tendency of modern research is to emphasise the idea of particulateness, for it looks as if the characteristics of organisms were often made up of elementary units, without intergrades, as sharply separated from one another as the chemical elements. But we must not lose sight of the unity of the organism, even in the one-cell phase of its being, and of the correlation of variations. A VARIATION 435 change in some particular kind of metabolism may reverberate through the whole body. Another important idea is that of temporal variations, that is to say, alterations in the ' time ' or rate or rhythm of metabolic pro- cesses, or in the duration of particular phases in the life-cycle. Many changes of great adaptiveness are probably due to the length- ening out of one chapter and the telescoping of another. In the influence of internal secretions in backboned animals there is a known method of effecting these changes in ' time '. Of great importance for our interpretation of evolution is the growing body of evidence that variation is often a much more definite organic change than was formerly supposed. There are many illustrations of progressive variation along a definite line, orthogenesis. Instances of mutations are accumulating, and if mutations come they usually come to stay. This also lessens the element of the casual and the need for over-burdening Natural Selection with the task of sifting from amid a crowd, and of ac- cumulating minute increments. Furthermore, variations occurring in a unified individuality are not likely to be stable unless they are congruent with the organisation already established. Thus there seems little warrant for talking about evolution as a " chapter of accidents ". It may well be that our conception of variability is fallaciously abstract unless we recognise that germ-cells are living organisms of great complexity telescoped down into a one-cell phase of being, and that they make essays in self-expression which we call varia- tions. These blind experiments of the germ-cells are submitted to the developing and adult organism to be tested in actuality. LECTURE XIV. DIRECTIVE FACTORS IN EVOLUTION SELECTION. LECTUKE XIV. DIRECTIVE FACTORS IN EVOLUTION: SELECTION. 1. Selection the Central Idea in Darwinism. 2. Logical Objec- tions to Darwinism. 3. Sentimental Recoil from Darwinism. 4. Changes in Selection Theory since Darwin's Day. 5. Scientific Critique of Selection Theory. 6. Subtlety of Selection Theory. 7. Sexual Selection. 8. Selection and Progressiveness. 9. Selectionist Interpretations and the Argument from Design. 1. Selection the Central Idea in Darwinism. THE central idea in Danvinism is the natural selection of the relatively fitter variants in the struggle for existence. Our understanding of Darwinism must therefore depend on our appreciation of what is implied in variation, in the struggle for existence, and in selection. A rough and ready understanding of it is easy, but when we are dealing with living creatures that is apt to mean misunderstanding, and so it has been. By the hasty-minded, and by those more anxious to score points than to get at the truth, Danvinism has been persistently misunderstood. This has been largely due to trusting to second-hand impressions instead of going to Darwin's own works. Natural Selection may be described as the process by which, in the struggle for existence, certain variants of a species, marked from their fellows by the pres- ence or absence of some innate character, are on that very account favoured with longer life or with more successful families than their neighbours, who are on that account ~ 439 440 DIRECTIVE FACTORS IN EVOLUTION: sooner or later eliminated. Darwin stated his theory in a couple of sentences : " As many more individuals of each species are born than can possibly survive, and as, conse- quently, there is frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of sur- viving, and thus be naturally selected. From the strong principle of inheritance any selected variety will tend to propagate its new and modified form." 2. Logical Objections to Darwinism. From Darwinism there have been several hasty recoils, some logical and others sentimental, but both due to mis- understanding. Let us take first the logical, and second the emotional or sentimental recoils. At a later stage we shall consider the emendations of Darwinism which further investigation has necessitated a very different matter. (a) It is a misunderstanding of Darwinism to dwell on the fact that Natural Selection is not originative, only direc- tive; that it is comparable to the action of pruning shears or of a sieve, not to the welling forth of a spring; that it corresponds to Siva, the destroyer, rather than to Brahma, the creator. That is quite true, but while Darwin sometimes spoke for brevity's sake of the creative work of Natural Selection, he made it quite clear that the sifting process could only operate on the raw materials which the variability of organisms brought within its scope. When we say that the strange shape of an evergreen in the garden is due to the gardener's shears, we do not forget the growing living plant. So when we say that the wing of a bird is the out- SELECTION 441 come of selection, we do not forget the varying organism, strong in endeavour. One forgives much to Samuel Butler in admiration of his genius, one forgives even the jibe that " Darwinism tries to explain how I am here by showing how my uncles, cousins, and aunts have gone away ". But it seems to us to promote misunderstanding when an expert writes in cold blood--" Darwin . . . left the question of variability open, a course which reduced his doctrine to the self-evident proposition that what was not capable of exist- ence could not exist ". . . . " Darwinism . . . explained how by throwing stones one could build houses of typical style ' (Driesch, History and Theory of Vitalism. Trans. London, 1914). (&) It also promotes misunderstanding to make very much of the fact that Natural Elimination is often a more accurate phrase than Natural Selection. A wonder-working gardener like Mr. Luther Burbank actively selects and fosters variants that catch his eye and seem to him to be promiseful ; what happens in Nature is in great part a weeding-out of the relatively less fit to given conditions. But it is familiar Darwinian doctrine to distinguish between ' lethal selec- tion ' which works by the discriminate elimination of the relatively less fit, and i reproductive selection 7 which works through the increased and more effective multiplication of the relatively more fit. As a matter of fact the weeding out of the relatively less fit must always to some extent involve the fostering of the relatively more fit which survive. 3. Sentimental Recoil from Darwinism. (A) The sentimental recoil from Darwinism may be illus- trated by those who shudder at the so-called automatism of the selective process. The raw material of novelties passes 442 DIRECTIVE FACTORS IN EVOLUTION: over an unending sieve which never ceases to sift; an un- certain fraction of the variants pass through the meshes and are ground to powder 'twixt the upper and the lower mill- stone; another uncertain fraction escapes and continues its kind. These are no mills of God, but of Moloch, and all is dread automatism. But it was to remove this misunder- standing that we lingered in a previous lecture over the struggle for existence, and saw that it included all the individual endeavours and answers-back which creatures with a will to live and abundance of resource make to their en- vironing limitations and difficulties. After allowing a little for chance, the relatively best candidates will come to the top in a number of wisely and accurately conducted exami- nations. This is not mechanical or automatic; neither is Natural Selection. We must recognise that Natural Selec- tion includes all the subtlety of endeavour, all the patient perseverance, all the indomitable insurgence, of living crea- tures. They share in their own evolution ; they often help to make the sieves by which they are sifted. (B) Another sentimental reason for recoil is because of the supposed grimness of the selection-method. " Contention is the vital force " ; rank individualism is the order of Na- ture ; " Each for himself : ' is the cry from every corner, and extinction take the hindmost. It is a vast gladiatorial show, said Huxley, this Nature, a dismal cockpit. But, as we have seen, this is a travesty. The struggle for existence is a metaphor, it includes every new endeavour after well-being ; it is rarely very intense between near kin ; it is often not competitive at all. One organism survives, indeed, by sharp- ening its claws and whetting its teeth, but another by increas- ing maternal care or mutual aid. Speaking of the Darwinian conception of the way in which SELECTION 443 evolution has chiefly been brought about, Prof. Arthur O. Lovejoy (1909, p. 93) writes: " The doctrine of natural selection represents Nature as a scene of monstrous waste and of universal conflict, a veritable bellum omnium contra omnes. It pictures the teeming Universal Mother as reck- less in the production of aspirants for life, but strangely parsimonious in her provision of the means of maintaining life, leaving to every one of the hungry children at her board only the privilege of snatching the food of his neigh- bours, only the grim alternative of destroying or being de- stroyed." . . . We quote this as typical of common carica- tures, not as representing Professor Lovejoy's own picture of Natural Selection. There is a tendency to exaggerate the destructiveness and instability of wild nature. Apart from man's interference, which is quite per se, cases of rapid disappearance of species, as in the Passenger Pigeon, are rare, and are very puzzling. What is impressive is the Live- and-let-Live equilibrium, the stability of species. Mr. E. C. S. Schiller writes that " Every species is in constant danger of extinction ", but one would like to have the evi- dence for such a statement. The fact is, that many species have attained to positions of extraordinary stability and security. 4. Changes in Selection Theory since Darwin's Day. It would be ominous if the theory of Natural Selection stood to-day as it did in Darwin's lifetime. Emendations have been made and saving-clauses have been added, and while extreme critics hold that the theory has been dis- credited, this conclusion is largely due, we think, to taking the theory in a wooden way and failing to realise its full significance. Before we consider typical criticisms, it will 444 DIRECTIVE FACTORS IN EVOLUTION: be convenient to discuss some of the positive changes in the theory. (1) There has been in a few cases a welcome demonstra- tion of Natural Selection at work. The theory is not merely a hypothesis as to what might have happened long ago; it is a statement of what does happen now. There is some actual proof of discriminate selection, where the survivors are shown to survive in virtue of the possession of particular qualities. Let us take a well-known diagrammatic instance, (Cesnola, Biometrika, 1904). The praying Mantis, Mantis religiosa, occurs in Italy in a green and a brown variety, the former usually on the grass, the latter usually on the withered herbage. The Italian naturalist Cesnola tethered twenty green Mantises among green herbage and a similar number of brown ones among withered grass. After seven- teen days they were all alive, having escaped the notice of their enemies. He tethered twenty-five of the green variety among brown herbage; all were dead after eleven days. In the converse experiment, of forty-five brown insects exposed on green grass, only ten survived at the end of sev- enteen days. Most of the Mantises were killed by birds ; five of the green ones were killed by ants. The experiment should be extended, but it proved the selective value of the coloration. If green and brown Mantises were exposed in a green country, the green ones would survive, the brown ones would be eliminated, and the selective death-rate would have reference to the particular quality of coloration. Simi- lar experiments have been recorded by Professors Poulton, Crampton, Bumpus, and Weldon all proving discriminate elimination. Prof. Karl Pearson has also demonstrated the occurrence of a selective death-rate in man. These demonstrations require more exposition than is here SELECTION 445 possible, but, as we are dealing with one of the most im- portant of biological theories, with the question of the direc- tive factors in evolution, we may cite from a previous dis- cussion two simple observations which illustrate discriminate elimination picturesquely (Thomson, Darwinism and Human Life, 1911). Prof. C. B. Davenport, of the Carnegie In- stitution for Experimental Evolution, had 300 chickens in a field, eighty per cent, white or black and conspicuous, twenty per cent, spotted and inconspicuous. In a short time twenty-four were killed by crows, and it was interesting to observe that only one of the killed was spotted. The elimi- nation seemed to be discriminate, and in wild conditions it would doubtless have led to the elimination of the conspicu- ous variants. It will be understood that we are not attach- ing great importance to any individual case, such as this, for criticism and corroboration are required all round; we are giving an illustration merely. In a heavy snowstorm at Johannesburg in August, 1909, many hundreds of trees were destroyed by the weight of snow on the branches. In many places the roads were blocked by the fallen trees. It was interesting, after the storm, to notice that the elimination was in a marked degree dis- criminate. The trees that suffered most were the imported Australian trees, such as the Blue Gums and Black Wattles, quickly growing, with soft wood, and with abundant foliage that caught the snow. On the other hand, the Deodars from the Himalaya mountains, constitutionally adapted to let the snow slide from their pendulous branches and acicular leaves, had hardly a twig broken. (2) In the second place, the position of the selection theory has been strengthened by a recognition of its mani- foldness. It takes several different forms, the logic of which 446 DIRECTIVE FACTORS IN EVOLUTION: is the same. When Darwin says " Natural selection acts by life and death ... by the survival of the fittest and by the destruction of the less well-fitted individuals ", he describes lethal selection. Insects with reduced wings or none at all abound in wind-swept islands like Madeira, the flying insects having been blown out to sea and destroyed. When Weismann points out that the animals best adapted to the colour of their surroundings will secure the most abundant food and multiply most prolifically, and will thus increase the numerical proportion of others like themselves, he is describing reproductive selection. If an advantageous character is linked to an increase of fertility it will tend to persist apart from lethal lopping off. In the cultivation of a lawn one may eliminate the weeds by direct lethal selection; but one may also stimulate the multiplication of the grass by giving it a specific food which is not profitable for the weeds. There is a special form of selection in the sometimes fatal combats of rival males, and in preferential mating when there is evidence of discrimination on the female's part. There is social selection between rival ant- hills, where community sometimes competes with commu- nity, and, at the other pole, there may be selection between potential egg-cells, the ovarian struggle sometimes ending in the survival of one out of many, and selection between the hundreds of sperm-cells in their race towards the ovum. Allowing a wide margin for chance, the most vigorous and perhaps the most sensitive spermatozoon will tend to succeed, and the elimination of the others by the blocking of the entrance to the egg will be for the advantage of the species. As Weismann suggested, it is also possible that fluctuations in the nutritive supply of the germ-cells, and inequalities in the vigour and assimilating power of the hereditary con- SELECTION 447 stituents or determinants, may result in an intra-germinal struggle and selection. But we need not go further, since our point is simply that the selective processes are probably more manifold than even Darwin realised. (3) Whenever we turn from expositors of Darwin to Darwin himself we discover afresh how subtle was his idea of the process of Natural Selection. We realise, for instance, that the selection need not imply a sudden elimination of the relatively less fit, for a persistently shortened life and a consistently unsuccessful family will work to the same result in the long run as lopping off heads. As Professor Punnett puts it: " If a population contains .001 per cent, of a new variety, and if that variety has even a 5 per cent. Selection advantage over the original form, the latter will almost completely disappear in less than a hundred genera- tions." In human affairs we may be thus encouraged in patience. It has also to be realised that the web of life has so fine a texture that apparently trivial differences in organisms may be of critical moment in determining the survival of those who possess them. And just as in animal courtship what determines the female's preference for one suitor out of many is very probably an irresistible tout ensemble of gifts and graces, rather than excellence in one particular decoration or quality, so in natural selection it may be that what gives survival value is often a general stability of constitution and efficiency of behaviour. In a well-known instance when 136 storm-spent sparrows were brought into shelter, 72 revived and 64 died. Careful meas- urements showed Professor Bumpus that the eliminated birds were less near the normal than those which survived. Ex- cept in one measured character, the range of variation was greater in those that succumbed. Thus while natural selec- 448 DIRECTIVE FACTORS IN EVOLUTION: tion may operate with great delicacy in reference to a sieve with fine meshes, it may also rough-hew and cut off in a crisis a large number of organisms which are in a general way less fit than their fellows. As Professor Bumpus said, general stability of structure was the essential characteristic of the surviving sparrows (Bumpus, 1898). (4) An interesting corollary to the selection proposition is that a relaxation of sifting may admit of exuberance. When organisms reach a position of relative security, as many species do, then, the criticism of circumstances being removed, there may be extraordinary abandon in the way of coloration and decoration. The limit is the stability of the constitution ; the risk is that some environmental change may involve a heavy tax on the exuberance which the condi- tions of relaxed selection tolerated. It may be one reason of the diversified brilliance of humming birds that they have few enemies. A clearer case is to be found in the coral- fishes, whose exuberance of coloration beggars description (see Reighard). It may be that the gorgeousness has been made possible by the safety of the labyrinthine reefs, and by the agility of the swimmers. Prof. J. P. Lotsy (1916) speaks of the bewildering diversity exhibited by a series of about 200 specimens of the Common Buzzard (Buteo buteo) in the Leiden Museum, " hardly two of which are alike ". " The reason probably is that here no selection has been at work, because this bird of prey is so strong that it. has practically no enemies in the regions in which it occurs." (5) Of great importance is the change that has been in- volved in our appreciation of Natural Selection by an in- creased knowledge of the raw materials supplied to the sieve by variability. As we have seen, discontinuous variations or mutations are not of rare occurrence ; there is a brusque SELECTION 449 passage from one position of equilibrium to another; the Proteus leaps as well as creeps. An advance marked from the first by a certain measure of perfectness is made at a stride, not by minute steps generation after generation. A copper-beech, a laciniate celandine, a hornless calf, a calculat- ing boy, or the like, just appears out of the inexhaustible conjurer's box. Now it is plain that as the list of these mutations or saltations grows in length, the lighter will be the burden that has to be laid on the shoulders of Natural Selection. Apart from the palseontological record it is only by analogy from the present that we can argue back to what occurred in the distant past, but it looks as if mutations were much more frequent than has been till recently supposed, and the more frequent mutations were in the past, the less work would there be for Natural Selection to do in the way of fostering small increments in a particular direction. It is quite premature, however, to think of abandoning the idea so characteristically Darwinian of the cumulative importance of minute advances. Many palaeontologists in- sist on the origin of new characters " by excessively fine gradations which appear to be continuous' (Osborn), and also on the frequent occurrence of orthogenesis, i.e., change in a definite direction without marked divagations. As Prof. H. F. Osborn says (1919), the palaeontological record often confirms the prophetic judgment of Aristotle: " Nature pro- duces those things which, being continuously moved by a certain principle contained in themselves, arrive at a certain end." We must be on our guard, however, against the possible fallacy of concluding, from the apparent orthogenesis in fossilised and surviving stages along an evolutionary line, that there was no zigzagness and pruning in the process. 450 DIRECTIVE FACTORS IN EVOLUTION: Types may have their waywardness gradually sifted out of them. The uniformity of the flow of cartridges from a test- ing machine gives a fallacious impression unless we dis- cover that they have passed through three siftings which reject the too heavy and the too light, the too long and the too short, and those whose calibre is too broad or too narrow. On the other hand, one of the impressions that we get from Prof. D'Arcy Thompson's magistral work on Growth and Form is that the variability of organisms runs on lines laid down by the conditions of the inorganic. Variations must conform to the trammels of surface-tension, minimal areas, stability, and so on; there is not an indefinite number of ways in which an aggregate of cells can be arranged ; one skull or leaf often differs from a related form in a way which might be described as a general deformation due, for instance, to a tilting of axes. The same general impres- sion of definiteness we get from considering what we have alluded to as temporal variations: one species often seems to differ from another in rate or tempo, and this fits in with Prof. D'Arcy Thompson's morphological illustrations, for dif- ferences of form depend in great part on different rates of growth in different directions. But even mutations and definite orthogenetic variations cannot dispense with the criticism of Natural Selection. There is ever a risk that they may go too far. It is easy to have too much of a good thing. The antlers of the Irish Elk which hastened the doom of their possessors are diagrams of the evolutionary adage Nequid nimis. If we accept De Vries's view that evolution is often effected by mutation, by sudden considerable jumps, this is contrary to the idea of Natural Selection working as an accumulator of small SELECTION 451 gains. But De Vries does not propose to dispense with the theory of Natural Selection. He attaches less importance to intra-specific selection, but not less to the sifting of species by one another and by the environment. Speaking of the Mutation-Theory, Prof. G. H. Parker writes (1913, p. 263) : " Organic evolution, then, is accomplished by occasional strides rather than by many oft-repeated short steps. This theory is in no sense antagonistic to natural selection. In fact, it works effectively only in conjunction with natural selection, for, after all, what determines whether a race showing a trait produced as a mutation will survive or not is natural selection. ... As De Vries himself rightly maintains, the mutation theory is significant only in con- nection with natural selection." 5. Scientific Critique of Selection Theory. As our whole view of Animate Nature is coloured by our position in regard to the scope and importance of the pro- cesses of selection, we must consider some of the most serious objections to the theory. We select three. One of the criti- cisms is thus clearly stated by Prof. G. H. Parker (1913, p. 256) : " The chief objection that has been raised against natural selection is one which was well known to Darwin himself, but which has been gathering strength for some years past. It is to the effect that the initial phases of a favourable variation, as conceived by Darwin, are too slight to be of use to the organism, and consequently they cannot come under the influence of the selective process. When the slight individual differences that Darwin laid so much stress upon are closely scrutinised, it seems scarcely conceivable 'that they could be, even in the long run, of life- and-death importance to an organism; in other words, that 452 DIRECTIVE FACTORS IN EVOLUTION: they could afford a starting-point for the formation of a new species. And when closely related species in nature are ex- amined, such as the different kinds of warblers, or of sedges, it seems impossible that the slight differences separating them should represent gaps produced by natural selection through an elimination of intermediate forms. Thus an in- spection of nature reveals a state of affairs which many inves- tigators have come to believe to be much too refined to be a product of natural selection." Some who admit that natural selection is " capable of rough-hewing a species ' doubt its -ability to put on " the polishing touches ". The answers to this objection are three. (1) The idea that established differences between species are too refined to be the work of natural selection, shows a lack of appreciation of the fact that the selection is often in relation to a very intricate and subtle web of life, where the shibboleth that decides survival or failure may be a very refined criterion indeed. (2) Vari- ations are sometimes correlated, and a minor variation which is not itself of sufficient magnitude to have survival value may be carried in the wake of one that has. (3) Some variations are not minute fluctuations, but are brusque muta- tions, springing fully formed into existence and therefore at once of a magnitude to be sifted in the sieves of natural selection. A second objection, also familiar to Darwin, is that indi- viduals possessing an advantageous variation would have to pair with others not possessing it, and that the new departure would be swamped by the inter-crossing. To this there are three answers : that similar variations often occur about the same time in several individuals ; that many factors of iso- lation operate towards reducing the range of inter-crossing and bringing similar forms together; and, thirdly, that many SELECTION 453 variations are of the nature called Mendelian, which do not blend, but are handed on in intactness to a certain propor- tion of the descendants. A third even more serious criticism has arisen out of the recent selection-experiments of the Danish biologist Johann- sen, the Dutch botanist De Tries, the American zoologists Jennings and Pearl, and others, which are to some extent at variance with the Darwinian view, that the average of a stock can be improved as regards a particular character by always breeding from those that show most of it. If the descendants of an individual high-class bean are kept apart, forming what is called " a pure line ", there are observable fluctuations of characters. Some are tall plants, others are short, and so on. But if the tails are selected out and bred from, or the shorts, there is no establishment of a tall race, getting gradually taller, or of a short race getting gradually shorter, nor is there anything to choose between the descend- ants of the tails and the descendants of the shorts. There is no departure from the average of the original pure line. From a mixed wild stock a selection may be made of par- ticular types which start pure lines or distinct races, but when the pure line has been started there is no further progress, select as one may. There is no getting beyond the mean of the inbred line. The reason for this seems to be that the fluctuations within the pure or inbred line are modi- fications or indents, and not transmissible. If selection of the best of a pure line does not improve the stock, how do the breeders succeed ? The answer is that their success is due to making a good start with a good line ; beyond the level of this they cannot pass without the intro- duction of fresh blood from another line. There are obvious reasons, however, why these facts from artificial selection 454 DIRECTIVE FACTORS IN EVOLUTION: must not be used hurriedly in depreciation of the role of selection in natural wild conditions, (a) Pure or inbred lines are not typical of wild stocks, in which cross-fertilisa- tion is of frequent occurrence, (b) It is dangerous to argue from very short-lived experiments to the age-long processes of Nature, (c) It is premature to deny the possibility of stable germinal variations occurring in a pure or inbred line. If one did, it might be the starting-point of a new advance. In any ease there remains a great role for Natural Selection in eliminating certain lines or races and favouring others in its ceaseless sifting. 6. Subtlety of Selection Theory. Natural Selection is a technical expression for a manifold and almost ubiquitous process of sifting, which discriminates in life and in death between the relatively more fit to the given conditions and the relatively less fit. It must always be thought of in the Here and Now, i.e., in reference to particular conditions of space and time. There are three reasons why it is important to keep this obvious fact in view, (a) It is a frequent and pernicious error to suppose that there is any sort of ceaseless winnowing towards an ideal of fitness, except perhaps self-consistency. The only common character of surviving variants is that they survive, they must have consistent viable constitutions suited to particular conditions, which may be those of parasitism or putridity. The fallacy of supposing that Natural Selection necessarily works towards ' fitness ' in the colloquial sense is largely due to thinking of the process abstractly and hypostatising it, and to misunderstanding the word ' fit ', which means merely relatively advantageous in given conditions, making for sur- vival in short. But the error is also due to a shrewd per- SELECTION 455 ception of the big fact that, after all, life has been slowly creeping upwards as the ages have come and gone. We shall consider this fact later on, but meanwhile it is necessary to be perfectly clear that being selected does not necessarily confer on the creature any dignity or approval. It means wholly and solely survivability in certain conditions, which may be those of parasitism or sloth. The value of survival, as judged by any human standard, depends altogether on the conditions under which survival is secured. Survival may be to a type that does not work for its living, but is an unpaying boarder inside another creature, or to a mere drifter in the stream of things, or to a rough egoistic combative type, much less desirable, when judged by a?sthetic or ethical standards, than a gentle, altruistic, fine-brained type for which the times were too stern. Survivability means little / in itself: one has to know the regional conditions and the price paid. (6) It is important, for a second reason, to remember that Natural Selection operates in great part with an external reference to an established system of inter-relations which we call the web of life. For it is this reference to an intricate sieve that enables us to understand how minute and rather subtle advances might have survival-value, or might turn the scale between success and failure. A nuance a shibboleth may be decisive. There are some kinds of fresh-water mussel which cannot continue their kind without the un- conscious co-operation of a particular species of fresh-water fish. The parasite which causes the disease of liver-rot in sheep cannot in Britain continue its race unless the free- swimming larva find entrance to a particular species of fresh-water snail Limncea truncatula, for other species do not seem to serve. There are some flowers which cannot 456 DIRECTIVE FACTORS IN EVOLUTION: be pollinated except by a particular kind of insect-visitor. We miss the significance of Natural Selection unless we realise its frequent specificity. Meredith speaks of Nature winnowing " roughly ", and that may sometimes be; but it is also a fact that she often winnows with a meticulous nicety. To sum up. In variation and selection we have, so far as we know, the chief factors of Animate Evolution. The method is theoretically very simple. A move is made and it is tested ; a new idea occurs and it is criticised. But this kind of formal summary of the tactics is quite fallacious. It conceals the heart of the matter, that living creatures with a will to live, with an insurgent self-assertiveness, with a spirit of adventure, with an endeavour after well-being- it is impossible to exaggerate the personal aspect of the facts, even if the words which we use in our ignorance may be too metaphorical do trade with time and have commerce with circumstance, as genuine agents, sharing in their own evolu- tion. There is abundant room for sympathetic admiration of the tactics of Animate Nature, though the strategy may -and, for science, must remain obscure. 7. Sexual Selection. (a) To illustrate still further the subtlety of the process of Selection we shall now consider how it works in the case of preferential mating. It was primarily in reference to secondary sex-characters that Darwin suggested his theory of sexual selection. Certain variations, e.g., in the improve- ment of weapons and food-catching apparatus, are favoured by natural selection in the course of the everyday struggle for existence; in the same way, variations which are advan- tageous in securing mates and consummating sexual repro- duction will be favoured by sexual selection. Darwin began SELECTION 457 with instances of the importance of masculine vigour and equipment when rival males compete for the possession of the females. " The strongest and, with some species, the best- armed of the males drive away the weaker ; and the former would then unite with the more vigorous and better-nour- ished females, because they are the first to breed. Such vig- orous pairs would surely rear a larger number of offspring than the retarded females, which would be compelled to unite with the conquered and less powerful males, supposing the sexes to be numerically equal ; and this is all that is wanted to add, in the course of successive generations, to the size, strength, and courage of the males, or to improve their weapons " (Descent of Man, 2nd Ed., 1888, Vol. L, p. 329). Now it is plain that forceful competition among rival males for the possession of a female or of several females, does not differ in kind from the ordinary struggle for food and foothold, except that it is strictly intra-specific. Darwin pointed out indeed (p. 349) that sexual selection is less rigorous than natural selection ; that it is less of a life-and- death affair ; that it operates through the unsuccessful males having fewer, less vigorous, or no offspring; and that it is not limited by the general conditions of life ; but there is in all this no departure from the natural selection position. This part of the theory, therefore, remains valid to those who regard natural selection as a vera causa. (b) Darwin went on to those characters that are useful in the recognition and capture of the females. When a male excels his neighbours in his capacities for finding, pursuing, and catching the female, sexual selection, he said, again comes into action. (Descent of Man, p. 324.) The male moth often finds his mate by the olfactory acuteness of his large anten- nae; some small crustaceans recognise the other sex almost 458 DIRECTIVE FACTORS IN EVOLUTION: instantaneously when there is chance contact in the water; in some fishes, recognition depends on colour and on be- haviour; many experiments led Goltz to believe that the male frog distinguishes the female by touch; in birds, visual and auditory impressions count for most; in mammals, the scent is often of chief importance (see S. J. Holmes, Studies in Animal Behaviour, Boston, 1916, pp. 219-328). Since cor- rect recognition of the one sex by the other is often of essential importance to the race, it is not surprising to find Darwin saying (Descent of Man, p. 324) : " But in most cases of this kind it is impossible to distinguish between the effects of natural and sexual selection." This part of the theory also remains valid, if one believes in selection at all. (c) Darwin primarily used the term sexual selection for all cases where sifting occurs in relation not to ordinary nutrition and self-preservation, but to pairing. It was only secondarily that he laid emphasis on the ' choice ? that the female is supposed to exercise in reference to rival suitors. An interesting confusion, which has misled some biologists, has arisen by a double use of the word selection. Darwin spoke of the female's selection, but it is perfectly clear that he recognised a large field of selection in which there was no question of selection or choice on the part of the female. (See Descent of Man, 2nd Ed., 1888, Vol. L, p. 323, foot- note.) Sexual selection meant, for Darwin, sifting in con- nection with mating, whether the female held the sieve or not. (d) In his next step Darwin used the word selection in a non-metaphorical sense : " Just as man can give beauty, according to his standard of taste, to his male poultry, or more strictly can modify the beauty originally acquired by the parent species, . . . so it appears that female birds in a state of nature have, by a long selection of the more SELECTION 459 attractive males, added to their beauty or other attractive qualities " (Descent of Man, 2nd Ed., 1888, Vol. I., p. 326). In many animals, at diverse levels of organisation, there is an elaborate courtship-ceremonial, allied, according to Groos, to play. It is sometimes on both sides ; it is usually for the most part on the male's side. It includes a manifold display of decorations, colours, agility, and vocal powers. Darwin's theory in this connection was simply this : if there are rival males, and if they are unequally endowed with structural and emotional equipment, or with the capacity of using this to advantage, there will be preferential mating on the female's part, and, other things equal, there will be a selec- tion of the type of male most successful as a suitor. It is the female who sifts, but the logic of the process is the same as in natural selection. (e) It is conceivable that pronounced and persistent differential mating might lead not merely to the establish- ment and augmentation of characters determining the result of the contest or the courtship, but also to a process of physio- logical and psychological i isolation ' (narrowing of the range of inter-crossing), and thus to an accentuation of the apart- ness of a species as regards crossing with related neighbour- species (see Karl Pearson, Grammar of Science, 2nd Ed., 1900, p. 418). (/) At this point attention may be directed to the impor- tant contributions to the natural history of mating to be found in H. Eliot Howard's monumental British Warblers (1907-1915). We venture to think that this acute and sym- pathetic observer exaggerates the instinctive at the expense of the intelligent element in the behaviour of birds, and that he is unnecessarily antagonistic to Darwin's theory of sexual selection, but his work is a rich treasure-house 460 DIRECTIVE FACTORS IN EVOLUTION: of reliable data. It is of great interest, for instance, to discover how much competition there is among the male warblers, before the females arrive on the scene, in the way of discovering and securely holding the most advantageous territories for nesting. Not less important is the evidence that the soberly coloured warblers do not fall behind bril- liantly coloured birds in the elaborateness and abandon of their display attitudes and poses. (g) Darwin was well aware of many of the difficulties besetting his theory. With his wonted candour he anticipated various objections, e.g., that the theory " implies powers of discrimination and taste on the part of the female which at first appear extremely improbable ' (Descent of Man, p. 326). The first very serious criticism came from Wal- lace in 1871, and was restated in his Darwinism in 1889. The most elaborate criticism as yet is surely to be found in T. H. Morgan's Evolution and Adaptation (1903), where no fewer than 24 reasons are given for rejecting the theory. Within our narrow limits we must confine our attention to the three criticisms which seem most important. There is, in the first place, an admitted difficulty in the scarcity of direct evidence that some of the males arc actually disqualified and left unmated. If all the males get mates sooner or later, then no discriminate elimination is effected. Prof. Karl Pearson has given statistical evidence of prefer- ential mating in mankind, but this is hardly procurable in the animal world. Darwin met the objection in various ways. He pointed out that in some species the males out- number the females, and that in some other species there is polygamy. If the more attractive males have in such cases an advantage in mating, the direction of evolutionary move- ment will be determined by them, and not by the handicapped SELECTION 461 residue of the unattractive. He also pointed out that the more vigorous and more attractive males would be accepted by the more vigorous females which are the first to breed, and this would imply a cumulative preponderance of the more vigorous and more attractive types. Even earlier hatch- ing of the young birds might be of critical moment. As a matter of fact, definite information as to the elimination of some of the males is by no means wholly lacking. Thus in diagrammatic illustration we may refer to some spiders where, as the Peckhams and others have shown, the female sometimes kills a suitor who does not adequately please her. That she may also kill a successful suitor is immaterial, since the mating has been accomplished. (See G. W. and E. G. Peckham, Observations on Sexual Selection in Spiders of the Family Aitidce, Milwaukee, 1889, p. 60.) In the second place, many critics have objected to credit- ing the female organism whether bird or butterfly with the power of ' choice ', and while comparative psychology has not advanced far enough to admit of many definite statements as to the subjective aspect of animal courtship, it may be granted that there is not in the ' choice ' of any female animal much that would correspond to a human weighing of pros and cons. But the point of importance is whether the mating is in any real way selective, preferential, dis- criminative. It has been proved experimentally that insects as well as birds may be selective in their eating: is the same true as regards their mating? It appears to us that the phenomena of mating recorded by Darwin, by Groos (Play of Animals, 1898), by Cunningham (Sexual Dimorphism, 1900), by Pycraft (Courtship of Animals, 1913), and so on, place the reality of some measure of preferential mating beyond doubt. Even if one adopts the modern view that 462 DIRECTIVE FACTORS IN EVOLUTION: the female does not choose the ' best ' out of a bunch of suitors, but rather remains unresponsive to the solicitations of males who do not raise her emotional interest to the requisite pitch, that is quite enough for the purposes of the theory ; and it is in agreement with Darwin's own re- mark about the female bird : " it is not probable that she consciously deliberates : but she is most excited or attracted by the most beautiful, or melodious, or gallant males ". A third objection is more serious. It is one thing to admit the reality of a somewhat vague preferential mating, it is quite another thing to credit the female animal with a capacity for appreciating slight differences in decorative- ness or musical talent or lithesomeness. Wallace's statement of this objection is well known. Referring to Darwin's four chapters in The Descent of Man, he says : " Any one who reads these most interesting chapters will admit that the fact of display is demonstrated; and it may also be admitted, as highly probable, that the female is pleased or excited by the display. But it by no means follows that slight differences in the shape, pattern, or colours of the ornamental plumes are what lead a female to give the pref- erence to one male over another ; still less that all the females of a species, or the great majority of them, over a wide area of country, and for many successive generations, prefer exactly the same modification of the colour or orna- ment (Darwinism, 189 9, p. 285). But the edge has been taken off this objection by Lloyd Morgan and others, who point out the gratuitousness of crediting the hen bird with a standard of taste or capacity for esthetic valuation. " The chick selects the worm that excites the strongest impulse to pick it up and eat it. So, SELECTION 463 too, the hen selects that mate which by his song or otherwise excites in greatest degree the mating impulse. Stripped of all its unnecessary aesthetic surplusage, the hypothesis of sexual selection suggests that the accepted mate is the one that most strongly evokes the pairing instinct ' (Habit and Instinct, 1896, p. 217). It may be insisted, however, that if individual excellence in attractive characters (such as plumes, singing power, dancing agility) does not appeal to the female, it cannot be determinative in preferential mating, and therefore its establishment cannot be effected by any process of sexual selection. Unless the female is somehow aware of the indi- vidual variation in question, the theory breaks down, and yet it is difficult to believe that the female is so meticulous in fastidiousness, so detailed in her preferential excitability. The answer, probably sound, is that the details count, not as such, but as contributory to a general impression. Each has its effect, but synthetically, not analytically. " Even when the female seems to choose some slight improvement in colour or song or dance, the probability is that she is simply surrendering herself to the male whose tout ensemble has most successfully excited her sexual interest 7 (Geddes and Thomson, Evolution, 1911, p. 172). (h) If one provisionally accepts the theory that a sec- ondary sex-character may have been established and aug- mented because it contributed to a decision in preferential mating, one has to face the further question of the signifi- cance or racial justification of the courtship-habits often so prolonged, elaborate, and exhausting. The sifting probably works well in keeping up a standard of racial fitness, for the most persuasive male is likely to be, among animals, the fittest all round. But there is surely more than this. 464 DIRECTIVE FACTORS IN EVOLUTION: To Groos and to Julian S. Huxley we owe two luminous suggestions. In his Play of Ammals (Eng. Trans., 1898, p. 242), Groos suggests that " in order to preserve the species the discharge of the sexual function must be ren- dered difficult, since the impulse to it is so powerful that without some such arrest it might easily become prejudicial to that end ". " This very strength of impulse is itself necessary to the preservation of the species; but, on the other hand, dams must be opposed to the impetuous stream, lest the impulse expend itself before it is made effectual, or the mothers of the race be robbed of their strength, to the detriment of their offspring." . . . " The most important factor in maintaining this necessary check is the coyness of the female; coquetry is the conflict between natural im- pulse and coyness, and the male's part is to overcome the latter" (op. cit., p. 243). !NTot less interesting is the suggestion developed by Julian S. Huxley in his remarkable study of the courtship-habits of the Great Crested Grebe, Podiceps cristatus (Proc. Zool. Soc. London, 1914, pp. 491-562). In the Great Crested Grebe the two sexes are practically alike in plumage, colour, and habits; but the courtship is extraordinarily elab- orate a self-exhausting ritual, " not leading up to or con- nected with coition ". Mr. Huxley believes that " the court- ship ceremonies serve to keep the two birds of a pair together, and to keep them constant to each other ". " Birds have obvi- ously got to a pitch where their psychological states play an important part in their lives. Thus, if a method is to be devised for keeping two birds together, provision will have to be made for an interplay of consciousness or emotion between them." The courtship is justified by the strength of the emotional bond it establishes. There is a " Mutual SELECTION 465 Selection " which is in a way " a blend between Sexual and Natural Selection ". (i) A survey of recent observations on mating, as in Mr. W. P. Pycraft's Courtship of Animals (1913), leaves an impression of an intricacy and subtlety that baffles descrip- tion. We agree with this distinguished expert as to the need for psychological as well as physiological interpre- tation. It is probable that no naturalist has studied a court- ship with the thoroughness that Mr. Huxley shows in his account of the Great Crested Grebe, and what is his verdict ? " Display and ornament do not act on the aesthetic sense of the female, but on her emotional state ; they are using the words in no narrow or unpleasant sense excitants, aphrodisiacs, serving to raise the female into that state of exaltation and emotion when alone she will be ready to pair. . . . But the element of choice does, in another form, remain. In animals such as Birds, where there is a regular pairing-up season, and where, too, the mental processes are already of considerable complexity, it is impossible to doubt but that mating may be, and in some species is, guided by impulse, unanalysable fancies, individual predilection." (/) In his Studies in Animal Behaviour (1916) Mr. S. J. Holmes has an interesting chapter on " the role of sex in the evolution of mind ". Let us take one illustration. " The primary function of the vocal apparatus of the Vertebrates was probably to furnish a sex call, as is now its exclusive function in the Amphibia. Only later and secondarily did the voice come to be employed in protecting and fostering the young, and as a means of social communication. And the evolution of the voice in Vertebrates doubtless influenced to a marked degree the evolution of the sense of hearing. It is not improbable, therefore, that the evolution of the voice, 466 DIRECTIVE FACTORS IN EVOLUTION: with all its tremendous consequences in regard to the evo- lution of mind, is an outgrowth of the differentiation of sex." There can be little doubt that the biology of the future will attach not less but more importance to sexual selection. For it seems likely that characters and qualities originally established in this way have often influenced both body and behaviour in reaches now more or less remote from the tides of sex-impulses. 8. Selection and Progressiveness. There is a very important reason why we should keep in mind the relation of Natural Selection to the Systema Natura? which has been gradually evolved, which is continu- ally becoming more complex, which is made up of numerous components, mostly stable and beautiful, often intelligent and purposeful. The reason is that we have here part of the explanation of the progressiveness of evolution. For, while there are blind alleys and other paths that turn back on themselves, the large fact is that on the whole evolution has been in the direction of increased differentiation and integration, of growing mastery and freedom. In this way Nature has led up to Man, her minister and interpreter. But how was it effected ? It may be that part of the secret is insoluble, that it is wrapped up with a tendency to complexify which may be seen even in the inorganic, where corpuscles form atoms and these molecules, where small molecules form large ones, and large molecules colloid masses, and so on. A fortiori it may be inherent in the very nature of an organism to complexify, to differentiate. We could suggest, however, that part of the riddle is solved when we carefully observe the process of Natural SELECTION 467 Selection, which operates in relation to an external Systema Naturae, the building-up of which is the work of aeons. As organisms evolved there was a pari passu complexifying of the web of life, and this extra-organismal registration worked towards conservation and towards further advance. For it is in relation to the external system that selection works. In the evolution of human societies much has always de- pended on the external registration of ideas and ideals. They form a framework of institutions and organisations, as stable as folk-ways and traditions; they become immortal in litera- ture and art; and this extra-organismal registration works both towards conservation and towards further advance. For it is in relation to the external system that selection works. It may be urged, however, that the social system is often unsound, that it may give fixed expression to the vicious as well as to what is noble, and that the result is to help degeneration not progressive evolution. The answer is sadly familiar, that this does occur; and that nationalities and their monuments alike are then swept from the stage. The difference in the realm of organisms is that we have there to deal with an external system which is the product of many millions of years, that the disintegrate elements which entered into it have for inherent reasons failed to stand the test of time. Like rotten stones in a building they have crumbled away. But they have been replaced by others more enduring. What we mean may be made clearer by a concrete instance. It was probably in the Carboniferous age that various insects became flower-visitors, that inter-relations began to be estab- lished between insects and flowers, between flowers and in- sects. The flowers evolving in their own way came to have flower-visiting insects (likewise evolving) as part of their 468 DIRECTIVE FACTORS IN EVOLUTION: environment, as part of the system in relation to which they were naturally selected. Similarly with the insects in rela- tion to i entomophilous ' flowers. And as the inter-relations became more and more intricate, more and more precise, they would tend to make the selection progressive. There may he a sort of momentum in the organism itself, for nothing succeeds like success. As Walt Whitman wisely said, " It is provided in the essence of things that from any fruition of success, no matter what, shall come forth some- thing to make a greater struggle necessary." As was said of old time : " For to every one who has shall more be given and richly given; but from him who has nothing, even that which he has shall be taken." Organisms run on a com- pound interest principle. But our present point is that the external web of life becoming ever more complex will tend to secure progressiveness. Whether or not our idea means as much as we think it does, its consideration should in any case put an end to the notion that Natural Selection is capricious. Both as regards the raw materials and the sieve, evolution is very far removed from being i a chapter of accidents '. 9. Selectionist Interpretations and the Argument from Design* This seems the appropriate place for a consideration of what has been called the Argument from Design. Discover- ing some of the thousand-and-one ways in which the structure and function of organisms are fit for the conditions of life, many keen-sighted and reverent naturalists of older days argued directly from the adaptations to the agency of a Divine Adapter. It was in a way a wholesome attitude, for the abundance of adaptations is a prominent fact in the SELECTION 469 realm of organisms: they have, as Air. Balfour si - " exq : site nicety and amazing c -r.xiiy ": they arc :. . : -. counted for; and some of them make for the com: . .-. : what has for Man great value. But it can hardly be ma. tained that the argument in its old form was logically sound. As Professor Lovejoy puts it (190.- . "from knowh._. through experience, that certain effects are caused only purposive human agency, we have no ground wh. U r for concluding that certain other effects, of whose causation have no experience at all. must be due to non-human pur - sive agency ". It has been called by logicians the fa 77(7: : transcendent inference, but perhaps there is a truth : transcendent inference in the idea behind the argumei::. Alanv naturalists know and admire three inonun. volumes by the late Prof. Bell Pettigrew entitled D Mature (190^ . They form a magnificent, generously illus- trated treasury of adaptations Bur not the least inter: g thin about these volumes is the fact that the author, with _ the thousand-and-oue fitnesses before him. found hi ins-, forced, like Darwin, to abandon the position of the Bridge- water Treatises, that one may find in adaptations the evi- dence of Divine Design. There is no doub: as I :hc reality of the thousand-and-oue adaptations: Why is the Bridge- water Treatise position untenable ' (1) It is a curious characteristic of some minds that they cannot give a living creature credit for doing anything very wonderful. They refuse to contemplate the possibility that what the creature does inav be accounted for in terms :: i itself. Thev insist on helping the organism on bv some * I extraneous introduction an Entelechy, a Purpose in X^:i: an clan vital, a Directive Intelligence, and so for:' What the older Xaturalists should have done before concluding 470 DIRECTIVE FACTORS IN EVOLUTION: their argument was to inquire how far the intelligence, which adaptations certainly suggest, may be resident as intelligence or some analogous form in the creatures themselves. Modern study shows that many animals work out their own salvation. (2) The second reason why modern naturalists do not occupy the old position is because their outlook is evolution- ist. When they scrutinise the magnificent series of adapta- tions more closely they discern less perfect stages of them in antecedent forms of life. The eye of a fly is an extraor- dinary instrument, but there is a long ladder of eyes ap- proximating to it. The community of hive-bees or of social wasps amazes us at first almost bewilders us, with its complexity and subtlety, but there is a long series of grada- tions connecting it with the life of solitary bees and wasps. Moreover, as we look around, we sec that many adaptations are still in progress, and very far from perfect. (3) The third reason is, that, given a sufficient crop of variations, plenty of time, and a process of sifting, the Darwinian can give a plausible and approximate we do not say an easy or complete account of the way in which most of the wonderful adaptations have been evolved. The hard-shelled Darwinian says : These effective adaptations you so justly admire are the outcome of natural tentatives and natural siftings. We assume that the forms of life are restlessly but not inconsistently variable, that they are con- tinually offering new qualities and characters to the sieve of selection, and that the conditions of life are such that they eliminate in a very discriminating fashion the relatively less fit. If these assumptions are granted, we can account for adaptations. The immediate operation of a Divine Adapter is a hypothesis of which, we say it with the utmost reverence, we cannot scientifically make any use. SELECTION 471 The idea of a Divine Designer is outside the scientific mode of formulation, to which it is an impiety not to be loyal, but it is not outside the right of interpretation which we claim as rational beings. It is a religious idea this of the Divine Designer; the question is whether it is incon- sistent with securely established scientific thinking. In our judgment it is not inconsistent. The old form of the Argument from Design has no longer more than a historical interest, but it may be reasonably maintained, it seems to us, that the general idea behind the argument remains. For if we free ourselves, as we think we must, from a purely mechanical evolutionism, and recog- nise organisms as genuine agents, we may see in the factors of evolution the relatively, though, of course, not absolutely self-sufficient, means of working out a purpose, or thought, or idea which was involved by the Creator in the origination of the first organisms, or wherever it seems clearest to begin. We must not forget the problem of the origin of the condi- tions that made Organic Evolution possible. That He the Unmoved Prime Mover has made things to make themselves and to go on perfecting themselves albeit they may be never separable in thought from Him seems a finer kind of crea- tion than Paley pictures. As Professor Pettigrew said in his Design in Nature (p. 820), "Natural Selection may be regarded merely as a process of so-called evolution by which the Creator works and accomplishes His purpose. Indeed the Creator, by conferring upon living matter in its simplest and lowest forms the power of appropriating the elements and building them up by endless elaboration and gradation from a monad to a man, proves Himself to be an infinitely more wonderful Designer than was ever dreamt of by even the most ardent teleologist." This surely strikes the true note. 472 DIRECTIVE FACTORS IN EVOLUTION: But it must be noted that it would not occur to scientific investigators, as such, to speak of the factors of evolution as means to an end. That is a point of view beyond science, though naturally taken by those who feel the extraordinary value and significance of certain results of evolution, such as the beauty of Nature, or the moving equilibrium of things, or the progressiveness of organisation, or the emancipation of mind, or the incomparable worth of a noble human life. SUMMAEY. The central idea in Darwinism is the selection of the relatively fitter variants in the struggle for existence. An immediate logical recoil from Darwinism has been based on the fact that Natural Selection is not originative, only directive; and that it is rather eliminative than selective. But these points are freely admitted by Darwinians; the recoil is due to a misunder- standing of insufficiently criticised phraseology. A sentimental recoil from Darwinism has been based on the sup- posed mechanical character of the selective process (but many organisms share as agents in their own evolution), and on the sup- posed grimness of the eliminative methods (but this is a very partial view). Since Darwin's day the theory of Selection has undergone some modification. Its position has been strengthened by the demon- stration of several cases of Natural Selection at work, by actual proof of a differential death-rate. It is not a mere inter- pretative hypothesis. Its position has been strengthened by a recognition of the manifoldness of the selective processes, e.g., lethal and reproductive. There has also been a clearer view of the probable consequences, e.g., exuberant decorativeness, that may ensue in situations where the elimination has been greatly relaxed. The estimate of the scope of Natural Selection is affected by the view taken in regard to the raw materials supplied. If these reach by mutational abruptness to some degree of perfectness, there is little for Natural Selection to do in the way of accumulating minutia3. If they are in large measure definite, then Natural Selec- tion has not to sift out the serviceable from a large casual crop. It SELECTION 473 has been shown by Johannsen, do Vries, Jennings, Pearl, and others that selection does not count for much within pure-lines or inbred stocks. The abundant ' fluctuations ' that occur there cannot be used as a basis for selection, for they are not transmissible, and are probably for the most part of the nature of modifications. As our whole view of Animate Nature is coloured by our estimate of the validity and importance of the Selection-Theory, it is useful to consider some of the more serious criticisms, e.g., that slight initial changes could not have survival value, that they would be swamped or levelled down by inter-crossing. ... It does not seem too much to say that the theory survives these criticisms and has been the better for them. It is very important to recognise that Natural Selection is a technical expression for a manifold, almost ubiquitous, and often subtle process of sifting, which has, in most cases, a particular ref- erence to particular conditions in time and space. It does not work consistently towards an ideal of fitness, but it eliminates inconsistent non-viable constitutions; it often operates in reference to an intricate web of life, and thus a nuance a shibboleth may have survival value; it operates, generally speaking, in relation to a Systema Natura; which has been increasingly elaborated through the ages, in which even ideas and affection get embodied, and this is part of the explanation of the progressiveness of evolution. Another part of the explanation of the progressiveness, which has always been a puzzle except to teleological interpretation, is what may be called organismal momentum. Organisms run on a compound interest principle. The question rises again whether the operative factors in organic evolution are more than complications or compositions of factors which operate in inorganic genesis. The answer is, much more. Natural Selection operates on what is not accounted for mechan- ically, and the sifting process itself is more than mechanical. What Ward has shown in regard to Subjective Selection is vitally impor- tant to an accurate view of the facts. The same conclusion mav be / reached from a different set of data, the phenomena of preferential mating. In variation and selection we have, so far as we know, the chief tactics of Animate Evolution. A move is made and it is tested; a new idea occurs and it is criticised. But a formal statement of the tactics is fallacious. It conceals the heart of the matter, that living creatures with a will to live, with an insurgent self-assertive- DIRECTIVE FACTORS IN EVOLUTION ness, with a spirit of adventure, with an endeavour after well-being -it is impossible to exaggerate the facts, even if the verbal sugges- tion is in our ignorance too metaphorical do trade with time and have commerce with circumstance as genuine agents, sharing in their own evolution. This should at least increase our sympathetic admiration of the tactics of Animate Nature, though the strategy remain obscure. Science has to do with description and formulation not with interpretation. Thus the selectionist account of the evolution of adaptations does not conflict with the general idea behind the old ' argument from design '. LECTURE XV. THE INDIVIDUAL AND THE RACE: HEREDITY- LECTURE XV. THE INDIVIDUAL AND THE RACE: HEREDITY. 1. Definition of Heredity, Inheritance, Nurture, Development. 2. Heredity a Condition of Evolution. 3. Modifications and Heredity. 4. The Organism as a Historic Being. 5. Nature and Nurture. 6. The Other Side of Heredity. 7. Heredity and Personality. THE water-vapour in the atmosphere condenses into rain which falls on the hills; in the cold night it is changed into ice, and next morning into running water again; at mid- day it changes once more into water-vapour. So the same material in the domain of the inorganic passes from form to form, and nothing is lost. A mineral changes into some- thing else and great aggregates are slowly transformed. " They say the solid earth on which we tread in tracts of fluent heat began." There is a similar sort of flux in the realm of organisms, in everyday metabolism, in wear and tear, in senescence. " And so from hour to hour we ripe and ripe, and then from hour to hour we rot and rot, and thereby hangs a tale." But apart from remarkable cases like Uranium liberating Helium and giving origin to Radium, which liberating more Helium may give origin to Lead, there is nothing in the domain of things to compare with sequence of generations that marks the realm of organisms. Individuals grow old and die; oftener perhaps they do not grow old, but are devoured ; in any case they give place to others in the pro- duction of which they often share. The corporeal individu- 477 478 THE INDIVIDUAL AND THE RACE: ality ceases to exist as such, yet part of it or something that was wrapped up with it continues, or may continue into an- other individuality. This is the genetic relation heredity, which has to be considered as a condition of evolution, and likewise as a factor in determining the individual life. 1. Definition of Heredity, Inheritance, Nurture, Development. A few definitions, representing condensed discussions, may be useful to start with. Heredity is the relation of organic continuity between successive generations, which secures the general persistence of resemblance between offspring and their parents, between progeny and their ancestors; it im- plies the continuance of a specific dynamic organisation of Avhich the germ-cells are usually the vehicle. In brief, hered- ity is the genetic relation between ancestors and descendants. Some use the word heredity to include all the causes or factors which determine the resemblance between individuals who are related to one another. But this resemblance is not wholly due to heredity. Others would say that heredity is the fact that like begets like; but it is more than that, including indeed the possibility of variations. Others would say that heredity is the past living on in the present, but perhaps inheritance is the fitter word to denote that fact. All these definitions suggest part of the truth, but it seems clearest to regard heredity as the organic relation between successive generations, a relation which secures persistence of characteristics and yet allows new ones to emerge. Whatever definition of heredity is adopted, it must be clearly understood that heredity is no mysterious force or principle ; it is a flesh-and-blood linkage, a continuity of germ-plasm, binding one generation to another. In pre-Dar- HEREDITY 479 winian days, men always spoke of heredity with a capital letter, as if it were a power that did things, as many people still talk of Evolution, but one of Darwin's many services was that he showed the linkage between generations to be amenable to scientific experiment and description. In mankind one generation may influence its successors by tradition and institutions, by literature and art, and in similar ways which are outside heredity in the biological sense. For the extra-organismal legacies the term social heritage may be usefully restricted, a usage which would leave Galton's term natural inheritance for all that is handed on by means of the germ-cells, namely the egg-cell and the sperm-cell. The natural inheritance includes all that the organism is or has to start with in virtue of its hereditary relation to parents and ancestors. In most mammals, where the unborn offspring is carried by the mother for a more or less prolonged period- -the two being bound together in a very intimate ante-natal partner- ship or symbiosis the natural inheritance of the offspring may be influenced by peculiarities in the available maternal nurture. The same is true in all cases where the parents, plants as well as animals, nurture the offspring. It is plain, though often forgotten, that ante-natal dints or imprints are not in the strict sense part of the natural inheritance. The word nurture, which Galton raised to the rank of a technical term, includes all manner of extrinsic influences, environ- mental, nutritional, and functional, which play upon the organism, or with which the organism plays. Modifications, as we have seen, are structural changes in the body of the organism directly induced in the individual lifetime by peculiarities in function or environment (including food, etc.), which transcend the limit of organic elasticity and 480 THE INDIVIDUAL AND THE RACE: thus persist after the inducing conditions have ceased to operate. They may be illustrated by the tanning of the skin under a tropical sun, or by the fattening of cattle, or by a callosity due to pressure. They are dints due to peculiarities in nurture, and have not been convincingly shown to be transmissible as such or in any representative degree. Finally, it may be noted that development is the realisation of the normal inheritance in appropriate nurture. 2. Heredity a Condition of Evolution. Heredity is not so much a factor in evolution, as a condi- tion of evolution. There would be heredity though there were no evolution, but there could be no evolution if there were not heredity. What is the role of Heredity? (a) Heredity involves arrangements which secure the per- sistence of a specific dynamic organisation holding fast that which is good. This role is achieved by a simple device the continuity of the germ-plasm or essential germinal mate- rial, a luminous conception mainly due to Galton and Weis- mann. It amounts to this, that in the course of development, often very early, some germinal material containing the in- tact inheritance is kept apart from specialisation and goes to form the germ-cells which become the starting-points of another generation. As Galton pointed out, in development the bulk of the germinal material of the fertilised egg-cell goes to form the ' body ' of the embryo, undergoing in a most puzzling way differentiation into nerve and muscle, blood, and bone ; but a certain residue is kept apart from the devel- opment of the t body ' to form the primordium of the repro- ductive organs of the offspring, whence will be launched in due time another similar vessel on the adventurous voyage of life. Thus in a sense the child is as old as the parent, HEREDITY 481 for when the parent is developing, a residue of unspecialised germinal material, retaining the heritable qualities in their intactness, is kept apart, and will eventually give rise to the germ-cells which form the starting-point of the child. As Weismann put it: In each development a portion of the specific germ-plasm contained in the parent egg-cell is not used up in the construction of the body of the offspring, but is reserved unchanged for the formation of the germ-cells of the following generation. So it comes to be that the parent is rather the trustee of the germ-plasm than the producer of the child. In a new sense the child is a chip of the old block. Or, as Bergson puts it, in less static metaphor, " life is like a current passing from germ to germ through the medium of a developed organism ". It appears that too rigid a contrast has been made between body-cells and germ-cells ; for groups of body-cells in plants, sponges, polyps, worms, Tunicates, and various other groups are able to develop into perfect organisms. It is safer to say that the germ-cells are those cells which carry the whole inheritance without allowing any of it to find expression until appropriate conditions and stimuli are forthcoming. They carry the whole inheritance in a form little liable to extrinsic influence and yet readily admitting of development. The general idea of germinal continuity is one of the most important contributions to post-Darwinian biology. It ac- counts for the inertia of the main mass of the inheritance, which is carried on with little change from generation to generation. For men do not gather grapes off thorns or figs off thistles. Similar material to start with; similar con- ditions in which to develop ; therefore like begets like. (6) The second role of the hereditary relation is that it allows of the emergence of the new and of the handing-on 482 THE INDIVIDUAL AND THE RACE: of the new. On the whole it makes for persistence, for in- ertia, but it also admits of the origin and entailment of novelties. An antithesis is often made between heredity and variation, but that b not well thought-out; the hereditary relation includes both the tendency to persistence and op- portunities for variation ; the antithesis is between the per- sistence of complete hereditary resemblance and the entail- ment of variations. (c) The third role of the hereditary relation is to shelter the specific organisation from the influence of parental modi- fications. It is not certain that the shelter is quite complete ; but it is indubitable that most of the dints made on the individual body are not entailed. An organism which be- comes subjected to a lasting change of temperature may, as the direct result thereof, acquire some adaptive peculiarity of great advantage; it would please our idea of economy to know that this individual gain could be handed on. An organism forced into a new habitat changes its functions adaptively and acquires, as the direct result thereof, a new dexterity. It would please our idea of economy to know that this gain could be entailed. So far as we know, this does not occur, and the reason is probably that such entail- ment of gains would involve also an entailment of losses, and that both are inconsistent with the arrangements which secure what is much more important, namely, the persistence of the specific organisation and of the germinal changes which it from time to time exhibits. If any organisms ever showed a strong tendency to transmit somatic modifications, the probability is that they would be eliminated. Our personal conviction, detailed evidence for which we have given elsewhere (Heredity, rev. ed., 1919), is that there is at present no good case warranting belief in the trans- HEREDITY 483 mission of exogenous somatic modifications. But several biologists for whom we have the greatest respect think other- wise, and, without any indecision on our own part, we would refer to the works cited in the bibliography under the names of Hartog, MacBride, and Semon. 3. Modifications and Heredity. In the absence of any convincing evidence that exogenous modifications acquired by parents can be transmitted to their offspring, either as such or in any representative degree, we have to face the question whether individual modifications have any evolutionary interest at all. It may be answered, first, that deeply-saturating modifications may influence the blood and other fluids of the body, or may alter the rhythm of metabolism so that the production of internal secretions is affected, and that these internal changes in the somatic environment may act as liberating stimuli on the germ- plasm and provoke variations. Prolonged exercise, e.g., in dancing, may lead to an exaggerated production of muscle- forming substance ; the myogenic metabolism may be en- hanced; this may be spread through the body, e.g., from limbs to heart ; it is conceivable that it might affect the germ- plasm specifically. The second answer is that suggested by Profs. Mark Baldwin, Lloyd Morgan, and H. F. Osborn, that an adaptive modification may serve as a protective screen for the indi- vidual until, perhaps, a germinal variation in the same direc- tion has time to arise and establish itself. What is not organically entailed may be acquired afresh in each suc- cessive generation. In an area where a dark skin was of survival value, acquired tanning might save many in- dividual lives until, perhaps, a germinal variation in the 484 THE INDIVIDUAL AND THE RACE: direction of inborn swarthiness had time to appear and establish itself. It seems to some quite incredible that the same modifica- tion should be hammered on for a thousand generations without inducing germinal changes in the same direction, but the difficulty is to find any direct or indirect evidence. It is likely enough that the long continuance of a particular modification might produce a metabolic change which might affect the germ-plasm, but the point is whether the effect on the germ-plasm would be to provoke a variation in the same direction as the modification. Mr. J. T. Cunningham and others have suggested that a well-defined modification may be followed by the liberation of some very specific hormone from the affected tissues, which might be carried to the germ- cells and there find a nidus for subsequent operations. But this remains a conceivable interpretation of what we do not know to be a fact. (c) Another consideration must not be forgotten, that it is in the personal life of the creature that the germinal variations are expressed, used, and subjected to criticism. The germ-cell or implicit individuality determines the cards, but it is the developed organism that plays them. It is highly probable that the adult creature sometimes seeks out a situation where its idiosyncrasy tells. Prof. James Ward has emphasised the importance of this organic selection. Environment selects organisms, but an organism may also select its environment. 4. The Organism as a Historic Being. The central idea in heredity is the persistence of a specific organisation and the associated specific activity. The past lives on in the present. The category of organism includes HEREDITY 485 the conception of the creature as a historic being. Let us think over this idea. (a) There is, in the first place, the remarkable persistence of the main body of the inheritance, with but rare divergence. There is racial inertia; the entailment of what is called specificity. As was said of old time, " All flesh is not the same flesh : but there is one kind of flesh of men, another flesh of beasts, another of fishes, and another of birds." This is confirmed by modern research, which has demonstrated, for instance, that the ciliated epithelium lining the windpipe of a dog is different from that from a rabbit. A fish can often be identified from a few scales, a bird by a single feather. This specificity goes through and through: thus Reichert and Brown (1909) have shown that the various species of mammals, so far as they have been tried, differ in the minutiae of their hemoglobin crystals. In this way it is possible to distinguish the blood of a domestic dog from that of a wolf, or even from that of the Australian dingo; red fox, grey fox, and Arctic fox are crystallographically specific ! Every creature has its own particular kind of colloidal substratum and its own particular chemical routine taking place therein. The largest fact of inheritance is the persistence of specificity, and we have here the reason why new departures of great moment are not likely to occur from specialised types. The relatively generalised types are most likely to be strikingly inventive. The antiquity of the various parts of the hereditary frame- work is one of the most impressive facts of biology. Galton has used the illustration of modern buildings in Italy which have sometimes been built out of the pillaged edifices of ancient times ; here is an antique column and there a lintel unified afresh. 486 THE INDIVIDUAL AND THE RACE: (b) The persistence of antiques is often seen with dia- grammatic vividness in the case of vestigial structures, which linger on in dwindled expression for ages after they have ceased to be of any use. As Darwin said, they are like the unsounded letters in many words, quite functionless but of historical interest. They have often been compared to the vestigial structures in clothes, buttons without cor- responding holes, and holes without corresponding buttons. So is it with the deeply-buried remnants of the long lost hind limbs that some of the whales still exhibit, or with the minute comb-like vestige of a gill in the spiracle of a skate. The animal world is full of these interesting relics as if the past were loath to relinquish its lien on the present. Man is an antiquarian in spite of himself, a walking museum of relics. A good instance is the vestigial third eyelid, larger in some races than others, occasionally with a supporting cartilage, but quite useless. It is the remnant of the nicti- tating membrane that in most birds and mammals does im- portant work in cleaning the eye. Similarly, the muscle t which moves the trumpet or pinna of the ear in many mam- mals, such as dog and donkey, and is useful in locating sounds, is vestigial in man, who moves his head about so 7 O / readily. Some men have it larger than others ; some may even become able to move their ears by wasting attention on the senseless effort. It may be noted that there is no great evidence of imperfection in the fact that vestigial organs are sometimes troublesome; it is too much to expect that there should be no tax on the stability of what is useful. Another instance of the past living on in the present is to be found in the persistence of ancient habits that have outlived their utility. According to Darwin, there is an HEREDITY 487 echo of the distant past when the dog hefore it settles itself to sleep turns round and round in the imaginary herbage of the hearthrug. The hand of the past is upon it in the passivity of sleepiness, and it does needlessly what its ances- tors did to a purpose. So in the donkey " we see signs of its original desert life in its strong dislike to cross the smallest stream of water ". We are told that some Scottish cows transported to unwonted conditions on an American ranch hid their calves in the thicket, and went to feed in the open in the old approved fashion of wild cattle. The novel circumstances were really primitive and they awakened a long dormant instinct. Many examples of this sort have been collected by Robinson in his Wild Traits in Tame Ani- mals, and while there is need for criticism, there can be no doubt as to the persistence with which the past lives on in the present. Many outcrops that seem quite perplexing in man are probably anachronistic stirrings of ancestral habits. (c) Another set of illustrations of the past living on in the present is afforded by the facts that are now familiar in regard to the staying power of certain unit-characters or Mendelian characters that are relatively superficial in nature, and cannot be regarded as forming part of the main frame- work of the inheritance. When we consider how the Ilaps- burg lip has persisted for four centuries in Austria and Spain, how night-blindness has continued to crop out for ten generations and in hundreds of individuals in one family history beginning with 1637, or ho\v brachydactylism (hav- ing the fingers all thumbs) may last for six generations, we realise that the hand of the past is living indeed, and inexorable. We have already mentioned the laciniate variety of the Greater Celandine (Chelidonium majus}, which sud- denly appeared about 1590 and has been breeding true ever 488 THE INDIVIDUAL AND THE RACE: since, and it is this sort of fact that we must include in our conception of the living organism, of Animate Nature, and of man in particular. That the innate defects as well as the excellences of the fathers are continued in the chil- dren far beyond the third and fourth generation is well known. (d) Another general illustration of the past living on in the present is to be found in the way in which the individual development tends to recapitulate the racial evolution. Long before the evolution idea was accepted, the suggestion was made, e.g., by Meckel, von Baer, and Louis Agassiz, that the stages in individual development correspond to grades of organisation in the animal kingdom. In post- Darwinian days, Haeckel recognised the importance of the recapitulation doctrine and stated it clearly in the light of evolution. He called it the fundamental law of biogenesis, and stated it in the familiar words: " Ontogeny is a recapitu- lation of Phylogeny." He also emphasised the contrast be- tween palingenetic characters, which correspond to those of the ancestral stock, and kainogenetic characters, which are relatively recent additions. The latter, he said, may disguise the former in a perplexing way; in any case, the recapitula- tion is general, not exact, and often shows great condensation. Fritz Miiller was another who did much to illustrate and corroborate the recapitulation-idea, e.g., in his Fur Darwin (1864). The recapitulation doctrine has suffered considerably at the hands of its friends, who have sometimes stated it in an exaggerated fashion. When Prof. Milnes Marshal said, " Every animal in its own development repeats its history, climbs up its own genealogical tree ", he was speaking pic- turesquely, for the recapitulation is general, not detailed ; it HEREDITY 489 often shows telescoping; and it is truer of stages in organo- genesis than of stages in the development of the embryo as a whole. It has also to be remembered that one term in the com- parison, the phylogeny, is very imperfectly known, so that assertions as to the exactness of the recapitulation must be taken with reserve. Needless to say, one must beware of the vicious circle of arguing from the development to the presumed ancestor, and then from the ancestor to its recapit- ulative rehabilitation in development. Another saving clause is that the individual development, especially when there are larval stages, may have its recapitu- latory features obscured by secondary adaptations to rela- tively recent conditions of life. Thus one does not look for recapitulation in the life-history of insects which have sub-aquatic larvae, for these have been secondarily adapted to a habitat which was not that of the ancestral stock. We may also recall the idea that life-histories have been adap- tively altered by lengthening out one chapter and telescoping another. Another saving clause concerns specificity, the individu- ality and uniqueness of every well-defined type. Increased precision of embryological work has shown that from very early stages in ontogeny an organism is itself and no other. An expert can distinguish an embryo chick a few days old from an embryo duck, before either of them shows any avian characters. There is only a technical difficulty in the way of distinguishing even the cells of an embryo mouse from those of an embryo rabbit, or those of an onion from those of a lily: the number of chromosomes is different. But a recognition of specificity from first to last is not inconsistent with admitting a significant correspondence between steps 490 THE INDIVIDUAL AND THE RACE: in individual development and steps in racial evolution. A tadpole is from the first in several ways an Amphibian and not a Fish, and yet in its two-chambered heart and branchial circulation it is for a time distinctively piscine. One reason why the ontogenetic recapitulation of phylogeny must be general, not precise, is that the successive gains made in the course of racial evolution are not superposed one upon another, but must be severally incorporated into the organi- sation and unified with it. The additions from millennium to millennium are not like new wings added to a house, for the tenements which we call individuals are continually dissolved, and there is re-unification at the start of each new life. We must remember too that antique characters grad- ually disappear, thus ancestral birds had teeth, but no embryo bird shows any trace of them. These saving-clauses are of importance, but the broad fact remains that the organism's inheritance, garnered for ages, does in many cases express itself in a step-to-step development, from the general to the special, which is in some measure a recapitulation of stages in what is believed to have been the racial evolution. Some illustrations must be given. On each side of the neck of the embryo reptile, bird, and mammal there are branchial pouches or gill-clefts which correspond to those which have a respiratory function in am- phibians and fishes, and may or do persist throughout life. In reptiles, birds, and mammals these pouches are on the whole transient, like fleeting reminiscences. The first seems to persist as the Eustachian tube from the auditory passage to the back of the mouth, and the thymus gland is connected with another ; but the rest pass away without persistent re- sult. They are echoes of the past. In embryos of the chick and of some reptiles, dwindling and transient traces of gills HEREDITY 491 in connection with the gill-clefts have been recently discov- ered (Boyden, 1918). Similarly, the embryos of higher Vertebrates show for a time a notochord, a primitive skeletal axis derived from the roof of the embryonic gut, and thus of endodermic origin. It persists throughout life in lancelets and lampreys, serving as the dorsal axis of the animal, as the forerunner of the backbone which, from fishes onwards, develops from the mesodermic sheath of the notochord. The notochord does not become the backbone, though perhaps serving as a sort of tissue-scaffolding for it, and every stage of the replace- ment of the notochord by its substitute the backbone is seen in fishes. Yet on to man himself the notochord continues to appear in development, a veritable antique ; it has its short day and passes, leaving but an unimportant trace behind. In the establishment of the brain, the skull, the heart, the kidneys, and other important structures in higher animals, the foundations are laid down on old-fashioned lines, not directly suggestive of what is to follow. In the individual organogenesis there is often a recapitulation of historical stages. The development of many an organ appears to the observer to be circuitous, as if the old paths had to some extent to be retrod, and yet the progress of a hundred thou- sand years may be condensed into one day. Another aspect of the same fact is that the developing embryos of, say, bird and reptile are for some days very much alike, moving on parallel lines along the great high- way of Amniote development ; but, sooner or later, about the sixth day in the case of the chick, their paths diverge and become distinctively avian and saurian. Thus does the past live again in the present with compelling force. How are we to think of it ? 492 THE INDIVIDUAL AND THE RACE: Ontogeny is the making explicit of the germinal organisa- tion, which is what it is because of phylogeny. The way in which an embryo moves towards a goal as if it had its future consciously in view is due to the fact that it is constitu- tionally determined by the past, which lives on in the present in a manner peculiar to and characteristic of living creatures. The ages that have gone have bent the bow in the plane along which the arrow of the individual flies. But ontogeny must not be thought of as the uncoiling of a wound-up spring, or as the unpacking of a marvellous treasure-box, or as a series of metabolisms which start one another in succession and enter into increasingly complex inter-relations ; ontogeny is a function of the individuality which is somehow con- densed within the germ-cell. Perhaps it is not, after all, very different from behaviour! The fundamental fact which we arc so far from understanding is that the fertilised ovum is at once the repository of ages of organic inventions and a unified individuality in the one-cell stage of its becoming. If we adhere to the conclusion that evolution has been a series of discoveries or inventions of the genuinely new, the further question is how the gains have become eriregistered in the germinal organisation, which must be thought of as becoming increasingly complex. There are two ways in which this enregistering may be thought of. (1) On the one hand it is conceivable that the individual acquirements and experiences of the fully developed individual may in some definite way affect the germinal organisation, and thus the progeny. In this way Lamarckians have thought of the germ-cells as being continually enriched by the gains of the individual organism, or reduced by its losses, and that in a quite definite and representative manner. There are very HEREDITY 493 few known facts which lend support to this view, but it seems premature to foreclose the question by any dogmatic denial of the possibility that individually acquired modifica- tions can leave representative imprints on the organisation, or, as some would say, on the unconscious memory of the germ-cells. It is possible that an increase of knowledge will show us that there is some hidden truth in the Lamarckian position; but the facts do not point that way at present. Deserving of consideration here are the remarkable facts of cellular habit or momentum in metabolism, expounded nota- bly by Prof. J. G. Adami (1918, p. 55 and p. 166). Pro- fessor Adami calls attention to facts like the following. Once the cells of the body of a rabbit have got accustomed to pro- ducing a counteractive or anti-toxin to ricin (a poison from the castor-oil plant), they may go on producing this anti- ricin for weeks or months after the original stimulus. There is an organic momentum. In the horse a single toxin unit of tetanus can lead in the process of immunisation to the production of 1,000,000 anti-toxin units. A cold in the head may continue for weeks after the causative agent has dis- appeared, and thorough sterilisation of the nose has been effected. The cells form a habit, it may be an entirely new habit, and it lasts, " an acquired cell variation becoming, if I may so express it, converted into a cell-heredity ". But the difficulty is to pass from such cases to the generations of multicellular animals. (2) The known facts point to the conclusion that the or- ganic materials of progress are supplied from within, from the fountain of change that there is in the germ-cell. If the metaphor be permissible, and we cannot get beyond meta- phors yet, the germ-cell is the blind artist whose many in- ventions are expressed, embodied, and exercised in the de- 494 THE INDIVIDUAL AND THE RACE: veloped organism, the seeing artist who, beholding the work of the germ-cell, either pronounces it, in the light of the suc- cess which it brings, to be good, -or else, when it spells ruin, curses it effectively by sinking with it into extinction. There is no difficulty in understanding how a germinal mutation, having arisen, comes to stay. That is provided for in the continuity of the germ-plasm. It is probably, then, by the entailment of the results of intrinsic germinal experiments, and not by the imprinting of the results of individual ex- periences, that the steps made in phylogeny become regis- tered in the germ-cells, and thus made expressible in the ontogeny for long ages to come. 5. Nature and Nurture. Development is always the result of an interaction between inherited nature (the germinal organisation and activity), and appropriate nurture (air, moisture, space, warmth, food, light, exercise, education, and much che). The two are complementary. Though the direction of development is mainly intrinsic, the degree of expression which the inherit- ance attains is conditioned by nurture. Theoretically, the point is of interest that there is what may be called an external heritage in relation to which the natural inheritance must develop. For we are ever apt to isolate too much, for- getting that the actuality is an association of organisms in a definite region. It is of obvious practical importance that the best possible nurture be secured. Otherwise promising variations may remain like sleeping buds, an inherited talent may remain hidden in a napkin in the ground. Hereditary characters are like seeds requiring soil and sunshine and rain. Negatively too it is always possible that alterations of nurture may prevent the actualism of inherited pre- HEREDITY 495 dispositions of a deteriorative sort. In Man's case nurture is very modifiable and largely under control ; much is made that is not born, and it rests with Man to determine whether it be ameliorative or the reverse. But it must never be for- gotten that the direct effect seems to be restricted to the individual. 6. The Other Side of Heredity. The past lives on in the present, that is what is meant by heredity. There is an inexorableness in the persistence, the so-called transmission, of all sorts of inborn peculiarities, except sterility of course, not only to the third and fourth generation, but far further. Sometimes it is a trivial feature like a shock of white hair ; sometimes it is a deadly vice of blood ; sometimes it is all bodily, leaving the spirit unblem- ished, as in certain cripples; sometimes it is a blot on the brain that affects the character, now in this way and again in that, but always perniciously. There is no gainsaying the fatalistic impression that the study of heredity forces upon us, and since heredity is the relation of organic or genetic continuity between successive generations, there can be no other side to it. But there is another side to the fatalism. (1) There is a growing solidarity among men and women of good-will; there is a wider recognition of the social or racial aspect of parentage; there is an increasing control of life. So that, while words are easy and actual doing is difficult, it is not speaking unadvisedly with our lips to say, that the reappearance of an evil past is not inevitable in the future : it may be blocked in the present. The transmis- sion of defects and weaknesses of a misery-bringing, race- weakening sort can be in some measure checked. A man. 496 THE INDIVIDUAL AND THE RACE: who is captain of his soul, need not submit to the lien that ancestry has over him. Brave words, of course; but history is full of brave deeds. One does not wish to say much about the way in which by a survival of Nature's regime in the Kingdom of Man rotten stocks come of themselves to an end; for the tragedy is that they often taint sound stocks by the way. (2) Moreover, it is ungrateful to forget that the hereditary relation, which depresses us when we lose perspective, secures the entailment of all manner of wholesome human qualities. The true inwardness of heredity is a holding fast of that which is good. (3) For characters that blend, if the occurrence of blend- ing characters be granted, it may remain true what Galton stated in his Law of Filial Regression, that there is a reg- ular regression or deviation which brings the offspring of extraordinary parents in a definite ratio nearer the average of the stock. This succession-tax is even-handed; the off- spring of under-average parents come nearer the mean just as do those of extraordinarily gifted parents. (4) The hereditary relation is such that it admits of variability, for the temptation to make a quite misleading antithesis between heredity and variation should be avoided. There is a strong specific inertia the first law of motion, as it were ; but there is a copious fountain of change the second law, as it were. Phrase it as we may, there is some- thing like creativeness, which is always supplying the new .raw material of progress. Unless we have quite misunder- stood evolution, it implies an emergence of novelties. It is like original thinking. (5) The quality of the nurture, largely in our own hands, determines the degree to which the buds of good qualities in HEREDITY 497 our inheritance may be made to unfold, and the buds of bad qualities may be kept more or less dormant. (6) There is an undeniable moulding power in changes of function and environment, and though the resulting modi- fications of our plastic organism do not seem to be genetically persistent, i.e., transmissible as such or in any representa- tive degree, they can be re-impressed, if desirable, on each successive generation. This is part of the biology of educa- tion. (7) Lastly, it must be recognised that in our social heritage., which is as supreme as our natural inheritance is fundamental, there are ever-widening opportunities for transcending the trammels of protoplasm. Wherefore, Sur- sum corda: Let us lift up our hearts. Mr. Bernard Shaw speaks of " the unbreathable atmos- phere of fatalism which is the characteristic blight of Dar- winism ". We have sought to show that as regards heredity there is air to breathe. It appears to us, moreover, that the fatalists assume a knowledge which they do not possess. A human inheritance is a very wonderful thing; it is very difficult to tell how much or how little a man has got. The son is told that he is handicapped by his father's defects, but it is quite possible that the father's innate defects were fewer and his excellences greater than ever transpired. For the fullness or sparseness of nurture determines the degree of expression which the inheritance attains in development. Of course there are limits. " He that will to Cupar maun to Cupar." " Though thou shalt bray a fool in a mortar, yet will not his folly depart from him." Our possibilities are hereditarily pre-determined, but can this be said of our actual personalities ? The higher the organism the greater its unpredictability within certain limits, the greater the 498 THE INDIVIDUAL AND THE RACE: power of the higher nature to modify what has undergone automatisation or cnregistration, the greater the capacity of selecting and altering the environment. We do not know all the evil that is in our inheritance, therefore we should not take too many risky chances. We do not know all the good that is in our inheritance, therefore we should give it every chance. Biology and history, as well as our con- science, give the lie to the mechanistic fatalism which asserts that we have not, in any measure, freedom of self-develop- ment. 7. Heredity and Personality. The greatest advance in the modern study of heredity has been the disclosure of unit-characters or Mendelian charac- ters. It is certain that there are numerous hereditary char- acters which behave in a distinctive and independent way in inheritance, being distributed as indivisible entities accord- ing to a definite scheme. They are clear-cut, either there or not there ; they do not blend or intergrade ; and they are infallibly present in a certain proportion of the offspring. They seem to be represented in the germ-cells by definite determinants, factors, or genes, the nature of which is un- known. Some have likened them to ferments; others to differences in the ultra-microscopic architecture. It is quite likely that several factors may be concerned in one character, or that one factor may influence more than one character. The gist of the Mendelian discovery is, in Pearl's words, this: " Hereditary differences behave, in the main, as discrete units, which are shuffled about and re-distributed to individ- uals in the course of the hereditary process, to a considerable extent independently of each other ; and in typical cases this re-distribution follows the simplest of statistical laws of HEREDITY 499 dispersal, the point binomial." In illustration of characters that exhibit Mendel i an inheritance, the following may be cited, the dominant condition which prevails over its alter- native in the first cross-bred generation being named first in each case: Hornlessness and the presence of horns in cattle, normal hair and long ' Angora ' hair in rabbits and guinea-pigs, kinky hair and straight hair in man, crest and no crest in poultry, extra toes in poultry and the normal number four, bandless shell in wood-snail and banded shell ; yellow cotyledons in peas and green ones, round seeds in peas and the wrinkled form, absence of awn in wheat and its presence, susceptibility to rust in wheat and immunity to this disease, two-rowed ears of barley and six-rowed ears, markedly dentate margin in nettle leaves and slightly toothed margin. Why one character should be dominant and its alternative recessive we do not know. It is often supposed that a dominant character implies something plus, the pres- ence of a definite ' factor ' ; while the corresponding reces- sive character implies the absence of that ' factor '. But it is difficult to hold to this consistently. The modern study of heredity suggests that our personal- ity is made up of many strands which go back into antiquity and which have a unique combination for each individual. The strands are ancient, but the individual, as Jennings (1911) says, " is a new knot ". And it seems an important fact that a good deal is known in regard to " the intimate material processes of the interweaving ". There is a fresh unification at the beginning of each individual life, a fresh unification that implies some measure of unpredictability and freedom from the past. The strands of each individual knot diverge before and behind us. " Those in my knot have come from a hundred 500 THE INDIVIDUAL AND THE RACE: others, and may later untie in a hundred still diverse. Of my characteristics I may say, like lago of his purse, " 'twas mine, 'tis his, and has been slave to thousands ". . . . " Our characteristics exist elsewhere in humanity and will continue to exist after that particular knot which forms the present self has been untied ' (Jennings, 1911, p. 906) t There is a certain organic immortality which is the lot of all, our strands live on. " It holds as well and in the same sense for him who leaves no children of his own as for the parent. 7 ' " Each of us is but a knot in a continuous web of strands that have, in other combinations, built up many persons, and will, in still new combinations, build up many persons. Thus as we have before taken part in the development of brute and of man, we may hope to take part in the development of superman' (Jennings, p. 910). It has been said that to find any enlightenment in the persistence of strands of personality in collateral lineages shows a very tawdry conception of what personality means and a very limited appreciation of the sanctities of human relationships. But this criticism is not quite fair: the biol- ogist whom we quoted and with whom we agree was simply making a biologist's contribution to one of the riddles of existence the apparent wastefulness of fine flowers that bear no seed. It is very unlikely that the same flowers will ever appear again ; the really fine individuality is unique. But it is not unlikely that approximations to the same pat- tern will recur. There is a conservatism in evolution, which retains qualities on collateral lines even when a particular lineage comes to an end. Mongrel ising makes for mediocrity, but eugenic marriages make for masterpieces. One can hardly reproach the order of Nature for cases where remedia- ble social conditions have prevented fine personalities from HEREDITY 501 the venture of parenthood. The deliberate or coerced celi- bacy of fine types may have implied in some cases an en- richment of the social heritage, but it is very unsound bio- logically. In regard to questions with a wider horizon than racial persistence the biologist must as biologist remain silent, but it is not unscientific to plead for keeping doors open till they must be shut. The personality of a genius whether intellectual, artistic, or moral is an amazing fact, perhaps further beyond the individuality of a dog than that is be- yond the unity of an amoeba. It is not the general body of the man that is distinctive, but the greatly increased com- plexity of the nervous system and the correlated new liberty and integration of thinking and feeling and willing. And this personality is still in process of evolution. Who shall fix its limits ? When, after thousands of years of discussion, all remains dark except in the light of Christianity, why should we continue the unending quest? But it is unlikely that man will ever cease from such adventuring, and it is not to be desired as long as the quest does not interfere with the discharge of his daily duties. As Simmias said in the Plicedo, shortly before Socrates was to die : " I will tell you my difficulty and Cebes will tell you his. I feel my- self (and I daresay that you have the same feeling) how hard or rather impossible is the attainment of any cer- tainty about questions such as these in the present life. And yet I should deem him a coward who did not prove what is said about them to the uttermost, or whose heart failed him before he had examined them on every side. For he should persevere until he has achieved one of two things: either he should discover, or be taught the truth 502 THE INDIVIDUAL AND THE RACE: about them ; or, if this be impossible I would have him take the best and most irrefragable of human theories, and let this be the raft upon which he sails through life not without risk, as I admit, if he cannot find some word of God which will more surely and safely carry him." SUMMARY. Heredity, the genetic relation between ancestors and descendants, between the race and the individual, has to be considered as a condi- tion of racial evolution and as a factor in determining the personal life. Heredity is the relation of organic continuity between successive generations, securing the persistence of resemblance between off- spring and their parents, between progeny and their ancestors, and is sustained by the continuance of a specific dynamic organisa- tion of which the germ-cells are usually the vehicle. The natural inheritance includes all that the organism is or has to start with in virtue of its hereditary relation, and is to be distinguished from extra-organismal legacies, such as Man's social heritage; from the results of ante-natal influence as in most mammals and flowering plants; and from exogenous modifications directly due to peculiar- ities in ' nurture '. Nurture includes all manner of extrinsic in- fluences, environmental, nutritional, and functional. Development is the realisation of the inheritance in appropriate nurture. Heredity is not so much a factor in, as a condition of evolution. It involves arrangements which secure the persistence of a specific dynamic organisation holding fast that which is good. This is effected by the continuity of the germ-plasm. Nevertheless it admits of the emergence and of the entailment of the new. It serves or tends to prevent the transmission as such of individual somatic modifications either for good or ill. The question arises in what way the personal life counts in evolution. Although there is not at present any convincing evidence of the transmission of individual modifications as such or in any representa- tive degree, it should be noted that some may serve as variational stimuli; that some may serve as adaptive screens saving the in- dividual until germinal variations in the same direction may emerge and establish themselves; and that it is in the personal life, often HEREDITY 503 of continuous experimenting, that the germinal variations are tested and sifted. The conception of the organism as a historic being is well il- lustrated by the facts of heredity and development. There is the inertia of the great mass of the inheritance, much of which is of very ancient origin. There is a striking persistence of vestigial structures and even habits. There is remarkable staying power in unit characters. There is an indubitable recapitulation of phylogeny in ontogeny, especially in organogenesis. The enregistering of past gains is probably to be thought of in the light of the continuity of the germ-plasm, for it seems that organic progress emerges from within and is not impressed from without. The individual organism is the outcome of a hereditary nature developing in an appropriate nurture. The direction of development is mainly intrinsic, but the degree of expression attained bears some relation to the extrinsic systematisation, what may be called the external heritage. In Man's case in particular, where the nur- ture is very subtle and very plastic, much may be made that is not born. A study of the facts of heredity engenders a fatalistic impression : the hand of the past has such a heavy grip. But " the other side of heredity ' must be considered, the persistence of the stable, the continual emergence of the new, the influence of nurture on the individual, and the dominance of the social heritage. It is important to bear in mind that each organism is in some degree a new individuality with some measure of indeterminateness, and made as well as born. The modern study of heredity forcibly suggests that the per- sonality is a unique combination of many strands which go back into antiquity. The strands are ancient but, as Jennings puts it, each knot is new. It is tied afresh at the beginning of each new life, and this implies some measure of uniqueness and freedom in the self. Our characteristic strands do in some measure exist in other combinations elsewhere, and may last on, unfortunately as well as fortunately, when our particular knot is untied. LECTURE XVI. THE EVOLUTION OF MIND AND MIND IN EVOLUTION. LECTUKE XVI. THE EVOLUTION OF MIND AND MIND IN EVOLUTION. 1. Of the Fact of the Evolution of Behaviour There Is No Doubt. 2. Difficulty of Understanding the Process. 3. Provisional Sketch of the Evolution of Behaviour. 4. The Efficiency of Mind in Everyday Life. 5. The Evolutionary Efficiency of Mind. 1. Of the Fact of the Evolution of Behaviour There Is No Doubt. IN a typical human life, thinking and feeling and willing bulk largely, and we naturally inquire into the historical setting of these capacities. We cannot make the mental states of animals the object of direct observation; on the other hand, we cannot believe that mental states began with Man. So we seek for indirect evidence that animals share them. Can we discern stages in mental evolution ? And this raises another question : In human evolution the prac- tical importance of mind is certain ; has it also counted in the evolution of organisms ? It should be possible to discuss these questions in a scien- tific way without going into the metaphysical question whether the stuff out of which the world is built can be thought of as independent of mind, and without discussing the difficult question of the relation of mind to body, if it be rightly called a relation. It goes without saying that we cannot derive mind from anything else of a different kind ; if we seem to do so we are deceiving ourselves with 507 508 THE EVOLUTION OF MIND verbal jugglery. It may also be said at the outset that if the genetic view we adopt here results in suggesting that animal behaviour is easy to understand or is a commonplace affair, then it is being wrongly stated. Whatever view we take as to the nature of mind and its relation to bodily ac- tivity, it is a fact that as we follow the main line of animal evolution, behaviour becomes more masterly, more plastic, more like our own. As regards behaviour the slipper-animal- cule is surpassed by the earthworm, the worm by the black- bird, and the bird by the cat. There is increasing freedom, subtlety, and resourcefulness of behaviour. Many will ad- mit this at once, who will not take the further step of supposing that the progressive evolution of behaviour is asso- ciated with a clarifying and strengthening of what, by anal- ogy with ourselves, we may call the stream of inner life- the flow of feeling, will, and thought. We suppose that there is a rill of inner life growing in volume until it becomes a stream, because as we pass from lower to higher animals there is more and more behaviour that we cannot fully de- scribe in purely physiological terms. But before we think tentatively of the stages in the evolution of behaviour, we must give heed to some preliminary considerations. 2. Difficulty of Understanding the Process. First, we must try to avoid any facile reading of the man into the beast. In ourselves we know that some stimulus often sets agoing a vigorous internal activity of thought- processes, involving an experimenting with imagery and play- ing with centrally aroused sensations. This goes on in our brain and it brings fatigue. It may be associated with movements in larynx and tongue, with speaking to ourselves, and with changes in eyes and brow and heart; but there is MIND IN EVOLUTION 509 not at the time anything to show for it in our explicit behaviour, and our neighbour offers us a penny for our thoughts. Yet our future action in the case of a genius, the history of the world may be modified by this hour of hard thinking. Is there that sort of inner life of the mind- body in animals ? We must not expect too much. Not only is our nervous system a much more differentiated and in- tegrated nervous system than that of even the highest ani- mals, but we have language and we have developed the pos- sibilities it affords of inter-subjective communion. A few animals have a limited vocabulary, but no animals have more than the primordia of language, so we must not sup- pose that the mental furnishings of animals are like our own. Some experts have warned naturalists that the search for reasoning, imagery, and the like among animals must forever remain futile. On the other hand, we should remem- ber that in our own case there is much in mind besides those inferences which we are accustomed to regard as distinctive of intelligence. There is a continuous flow of mingled sen- sations, perceptions, ideas, feelings, desires, and volitions, a stream sometimes clear and peaceful, sometimes muddy and turbulent. It is probable that among the lower animals, the flow does not show much in the way of perceptions and ideas, still less in the way of experiments with these. We know that in our own individual development the earlier stages are largely pre-intellectual, mainly emotional. It is extremely improbable that the starfish laboriously disarming the sea-urchin has made any inference on the subject, for its nervous system has no ganglia ; but it is difficult to make sense of the operation without crediting the creature with conation, with something of the nature of endeavour, not necessarily with full antecedent awareness, but with a de- 510 THE EVOLUTION OF MIND termination of action in relation to the result that will accrue. Another great difficulty lies in the fact that at stage after stage, as we have seen, there is a tendency to organisation or automatisation of capacities for behaviour, and if we attend too exclusively to these we are apt to get the im- pression that the naturalist's suggestion of mind is a mere courtesy to the psychologist. But it is necessary to look into the less conspicuous deviations from routine which some- times show the hand of mind on the reins, and to inquire into the stages of initiative and testing which may have pre- ceded the automatisation. Perhaps the biggest difficulty of all is to think of germinal variations supplying the appropriate materials for the evolu- tion of complicated instinctive behaviour or for capacities of perceptual inference. Nowhere does the problem of the origin as distinguished from the survival of fit variations appear so baffling as here. 3. Provisional Sketch of the Evolution of Behaviour. What, then, shall we say of the Evolution of Behaviour? (a) A starting-point may be found in the tentative move- ments of simple creatures, swimming about in the pond, called hither and thither by slight differences in temperature, oxygenation, and the like, or, if there is no particular stim- ulus, moving in straight lines, or curves, or spirals ex- pending their energy, expressing themselves in modes of loco- motion which are often characteristic, yet every now and then striking the note of tentative endeavour. There is an occasional new departure, some experiment, a hint of the bent bow. As Professor Jennings has graphically described, they amoaba hunts another amoaba, captures it, loses it, recaptures MIND IN EVOLUTION 511 it, loses it. Much importance must be attached to simple searchings and probings. As the late Mr. Darbishire put it: " If Necessity was the mother of Invention, Curiosity was almost certainly its father." (&) At an early stage there must have been established a number of particular answers to stimuli, which in the case of Unicellulars may be called organic reactions, keeping the word reflexes for creatures with a nervous system. A good illustration is the answer-back so familiar in the case of the slipper-animalcule, Paramecium. To every hurtful stim- ulation it gives the same answer: it reverses its cilia, it retreats, it twists a little on its axis, it feels its way, and goes full steam ahead often in this way avoiding the ob- noxious stimulus. The capacity of exhibiting this uniform reaction is organised or enregistered in the creature; and these ingrained capacities increase in number. (c) The next step is the ( trial and error ' or perseverance procedure. One reaction is tried after another, till, it may be, one of the movements relieves the creature from stimula- tion. The Stentor reacts in four different ways to the micro- scopic dust which the experimenter showers on it ; three an- swers are ineffective, the fourth saves the situation. There is a persisting state of the organism which varies the answers, there is probably a simple expression of conation or en- deavour. (d) The main line is continued in such behaviour as is illustrated by multicellular ganglionless animals like star- fishes. There is persistent co-ordination of acts towards a definite result. There is sensori-motor experimentation. Our picture here is that of the brainless starfish persistently disarming the brainless sea-urchin, wrenching off the pedi- oellarue from area after area. This is purposive behaviour, 512 THE EVOLUTION OF MIND but the purposiveness has not reached a perceptual level. Consciousness is at work, and its " precise function in sen- sori-motor action is to grasp the unique combination of stim- uli, each of which having its special reaction modified by the concomitant reactions, there follows a response appro- priate to the unique situation as a whole ' (Hobhouse, Mind in Evolution, 1915, p. 62). (e) With the establishment of a nervous system there was opened up the possibility of a new kind of hereditary autom- atisation or organisation, that of reflex actions and tro- pisms. The former are usually movements of parts of the animal, the latter movements of the whole creature. A re- flex action is the predetermined result of the activation of an inborn structural arrangement of receptor, conductor, and effector, which gives a uniform response to a given stimulus. It may be very perfect from the first, or it may improve by practice, or it may result from individual habituation: but typically it is an outcome of pre-established hereditary organisation, definite linkages of sensory neurons, associa- tive neurons, motor neurons, and muscular elements. In effect reflex actions seem purposive, but in process they are organisational. If there was originally an operative pur- posiveness, it has receded into pre-formed structure. Our pictures are of the sea-anemone closing its tentacles on a victim, of the nestling opening its mouth at the touch of food in its mother's beak, of the starfish surrendering an arm in the spasms of capture, of the young mammal sucking whatever is put into its mouth. Antecedent to reflexes there is more or less random flow of activity which is now and then definitised in experiment and endeavour. Reflexes im- ply the establishment of definite channels for the flow. Tropisms are more or less obligatory movements of the MIND IN EVOLUTION 513 whole organism, or of a large part of it, which automatically make towards securing physiological equilibrium in refer- ence to particular stimuli. Thus an organism moves towards or away from light and heat, electric currents and diffusing chemical reagents, water currents, and the earth and so on. It must not be said that heliotropic animals desire the light or dislike the darkness ; the tropisms are more or less forced movements which work automatically like a gyroscope. Our evolutionary theory is that reflexes and tropisms are economical automatisations, enregistrations, or organisations of capacities which are continually being called into action in the ordinary life of the creature. They require neither thought nor endeavour; they are ingrained and almost as much part of the constitution as, say, breathing movements. Their survival value is (1) that they admit of the rapid automatic execution of life-preservative or species-preserva- tive movements (an automatism for which in unusual con- ditions there may be a heavy tax to pay) ; and (2) that they leave the organism more free to use, if it can, the second string of purposive endeavour. (/) The main line continues in a kind of behaviour which shows evidence of i learning ', of utilising previous experi- ence to compass an end which is not necessarily immediate. The note of inference is beginning to be sounded. There is experimentation and correlation at a higher level than that of the starfish. It is the dawn of intelligence, and may be illustrated by cases like the following. A young octopus trying to capture a hermit-crab is stung by the sea-anemone which is the crustacean's partner. It avoids further en- counters. Old octopuses, however, learn to extract the her- mit-crab without touching the sea-anemone. Prof. Lloyd Morgan calls this profiting by experience through the exer- 514 THE EVOLUTION OF MIND else of intelligence. Dahl relates that when a spider is given a fly that has been steeped in turpentine, it will not for a time dart at another fly of that species. This is like simple learning. (g) The improvement of the brain opened up a new pos- sibility in the way of hereditary organisation that of in- stinctive behaviour. In virtue of inborn nervous predispo- sitions the animal seems to be from the first aware of the significance of certain stimuli and configurations, and obeys an impulsion to a definite routine which is singularly effec- tive, though more or less independent of practice. Pure instinctive behaviour is well illustrated by ants, bees, and wasps; but there and elsewhere it may be mingled with experimental, including intelligent, behaviour. Of instinctive behaviour very perfect in its first performance many pictures rise in the mind : the chick neatly removing the top of the imprisoning egg-shell, the month-old kitten exhibiting without imitation " almost a complete repertoire of move- ments used by the adult cat in catching and killing mice ", the young guinea-pig nibbling at a carrot at the end of the first day after birth. In illustration of instinctive activities that improve or change under various influences we may recall the pecking of chicks and the singing of some birds. Of the serial succession of steps in instinctive behaviour there is no better illustration than the way in which the Yucca moth on its first flight visits and pollinates the Yucca flowers and lays eggs in the ovary. (h) The next level is that of intelligent behaviour, which is characteristic of the higher reaches of the big-brained line of evolution. It implies trial and error experimenta- tion on subtler lines and more definite profiting by ex- perience. Psychologists interpret it as implying i perceptual MIND IN EVOLUTION 515 inference ', some working with ideas. It is reflective and inferential, as contrasted with instinctive and intuitive. When the Greek eagle lets a tortoise fall from a height on the rocks below so that its strong carapace is broken, when beavers cut a canal right through an island in a big river a task not practically justified till completed, when a collie dog at the bidding of a few sounds and signs accomplishes a really difficult thing in the way of sheep- driving, it is probable that we have to do with intelligent behaviour. We have seen that., at various lower levels of behaviour, the perfecting role of practice is recognisable, and this is the case also at the level of intelligence. We are familiar with the individual habituation of exercises which originally required attentive selection and detailed control. Certain structural changes in the nervous system come about as the result of frequent performance, and what was at first la- boured becomes very automatic or so facilitated up to a certain point that the mind is free to attend to finishing touches. It is not known that the results of individual habituation can be entailed in a representative way on the offspring. (i) The climax is the rational conduct occasionally ex- hibited by Man. We cannot describe such conduct without using general terms ; it involves experimenting with ideas, conceptual as distinguished from perceptual inference; it is controlled with reference to an ideal or conceived purpose. Man has his reflexes and a little instinctive behaviour; most of his activity is either intelligent, or was originally intelligent, but has become habitual; the point is that, if occasion arise, Man may instantaneously .pass from a lower level to that of rational conduct. 516 THE EVOLUTION OF MIND When we look back over the vaguely discerned succession of modes of behaviour, we detect what may be called the tactics of the evolutionary advance. At level after level, there has been an organisation or automatisation or enregis- tration of behaviour so that an organism can do things effectively without having to think about it. The answer comes pat, and there is an economy of time and life. In reflex actions, tropisms, and instinctive behaviour we see the activation of capacities which have become part of the hereditary constitution. The great result has been that the organism, freed from having to attend to and control these organised activities, has been able to push on to finer issues. As individuals we are aware of this result being attained by habituation, but there is little warrant for supposing that the successive organisations we have referred to have arisen by the entailment of the results of often repeated performance. We say this because we do not know how it could be arranged, because we have no evidence of the transmission of intelligent-habitual capacities, because some of the most striking pieces of instinctive behaviour occur only once in a lifetime, and for other reasons. How, then, could the successive organisations be accom- plished ? The probable answer is that they are all due to germinal variations in the direction of a complexified nerv- ous system. New departures which have been called, from the psychical side, ' inborn inspirations ' prompted changes in behaviour, and these were tested and sifted in the indi- vidual lifetime. For a time the germinal variation might be in the direction of differentiating and integrating the brain; for a time there might be a specialisation in the seat of some particular activity; and again there might be varia- tion leading to short-circuits. MIND IN EVOLUTION 517 We are still at the stage of metaphor in regard to the factors in the evolution of behaviour; but metaphor is less dangerous than false simplicity. Our metaphorical picture is this the germ-cell just beginning to develop is an im- plicit organism of great complexity, an individuality in the one-cell phase of its being, a mind-body or body-mind tele- scoped down. It varies, it makes experiments in internal re-arrangement, in self-expression. It is a blind artist, its sketches are submitted to the criticism of the fully-formed organism, the seeing artist, who will put them in the proper light and bring out what there is in them of value. If the Amoeba has in its small way a mind, an aspect of itself corresponding to our mind, and if the Amoeba uses it when it goes a-hunting, two not unreasonable hypoth- eses, then it may be that the germ-cell has also its analogue of mind a not unreasonable hypothesis, since it develops into a creature with a mind. And this leads us to the hypothesis that the more momentous variations may be in- explicable if we keep only one aspect of the germ-cell in view. And if so, could there be a more relevant opportunity for the mental side showing itself than in variations which lead to new departures in behaviour ? In any case, the hypothesis that hereditary organisation of capacities of behaviour comes about by the entailment of the results of individual practice, experimenting, and learn- ing cannot be readily maintained. On the other hand, while it is difficult to think clearly of the origin of .great improve- ments in behaviour by germinal variation, and of the relative automatisation of them arising in the same way, there is no special difficulty in understanding their persistence on this theory. For variations that arise from within have often great staying power in inheritance. 518 THE EVOLUTION OF MIND The Germinal Origin of Improvements in Instinctive Be- haviour. We must linger over the difficulty, which many biologists feel acutely, of trying to account for improvements in instinctive behaviour by variations in the germ-cell. When an organ, such as the proboscis of an elephant, has shown in successive ages a gradual increase and differentia- tion, as the skulls of fossil Proboseidea seem to indicate, the non-Lamarckian evolutionist supposes that this is due to the selection of variants in the direction of elongation, these variants being the expressions of appropriate changes in germinal organisation. The change in germinal organisa- tion, say a strengthening of certain primary constituents, operates during the active process of proboscis-development, or of proboscis-growth, for it need not begin to exert its influence until long after the foundations have been laid. Thus a long-billed bird need not show much or anything in the way of a long bill until after it is hatched. The general idea is that an improvement of structure comes about as the expression of a germinal variation which asserts itself during the activity of development or growth. It is not necessary to think of it as asserting itself only once, for the highly differentiated structure, such as a snail's horn or a newt's lens, may be regrown if it be lost. The germinal variation includes a residual capacity (localised at the base of the horn or in the tissue near the lens) for reproducing or regenerating what has been lost. The general idea, we re- peat, is that a cumulative germinal variation, implying a per- fecting of some part of the germinal organisation, expresses itself in the course of generations in a cumulative improve- ment of a certain routine of developmental or growth activity. If this be admitted as conceivable, then it is not a great step to pass to the improvement of instinctive activities as MIND IN EVOLUTION 519 the result of progressive germinal variations and, of course, the personal testing of these. For the line between develop- ment and the expression of instinctive capacity is hard to draw. Both are actualisations of the implicit, the ingrained, the enregistered. Both are expressions of * organic memory '. As M. Joussain says (1912, p. 156), "Instinct is a pro- longation of the organising work : the effort by which the chick breaks its shell, frees itself from the debris, and be- gins to walk, is a continuation of the development by which its organs have been built up in the egg." He proceeds to say, though the speculation is not necessary for our point : " If the final stroke of the beak is conscious and voluntary, the work immediately antecedent must likewise be so, and thus back- wards. It is, then, by its own effort that the egg is developed into a bird." . . . But this will sound absurd to those who are satisfied with the simplicist formulae of the mechanical school. Organic Memory. In his interesting Esquisse d'une Phi- losophie de la Nature (1912), M. Joussain makes much of the conception of organic memory. " The transition from mechanism (tropism?) to instinct and from instinct to intelli- gence, as likewise from automatism to spontaneity and from spontaneity to freedom, is correlated with the extension of memory. In the animal, the complexity and differentiation of the organism are correlated with the extension of specific memory. . . . The relative independence of the organism in respect to its environment increases with its complexity and differentiation, and consequently with the specific memory. The higher the animal's degree of organisation, the more it is capable of altering its reactions in answer to stimuli from without, the more reserve of energy it has and freedom in using it. The independence of the creature is thus greater 520 THE EVOLUTION OF MIND in proportion to the extent of its remembrance, and in this sense one may say that memory enfranchises it from the dominion of matter." It seems to us, however, that there is need for discrimina- tion here between the little-brain type, with its climax in ants and bees, and the big-brain type, with its climax in dog and horse. The enregistration of capacities of effective rou- tine reaches a high degree of perfection in ants and bees, and we may call it racial memory if we please. But while it makes for mastery of the usual, it does not bring any gift of freedom not even of educability. It is an enregistra- tion of capacities of concatenated reflexes, but certainly not of reflection. It is a memory that kills originality. We agree therefor with those who distinguish the enregistering of instinctive capacity from the enregistering of intelligent capacity, the power of discerning relations, of controlled not reflex behaviour. It is comparable in a way to the experi- ence of many students who remember little of what they have learned, read, or even solved, but who have as their reward a capacity of rapid judgment. 4. The Efficiency of Mind in Everyday Life. There is no use going farther without facing the position of those who maintain that all this discussion is an unneces- sary complication of the problem, who believe that to speak of an inner life besides metabolism is only a fagon de parler, who regard mind at the best as a useless epiphenomenon. The first respiratory movements of the newborn offspring are commanded by delicately adjusted inborn structural ar- rangements in the medulla oblongata ; these are set into activ- ity by external stimuli or by slight changes in the alkalinity (Hydrogen-ion concentration) of the blood; and these again MIND IN EVOLUTION 521 are due to a slight asphyxia resulting from the withdrawal of the maternal circulation. So when it comes to sucking, swallowing, digesting, and the like, appropriate stimuli pull the trigger of pre-formed adjustment, and one reflex process evokes another, and so the creature gets on. We have an inherited set of triggers called ceptors, con- tact-ceptors, chemical-ceptors, thermal-ceptors, and so on; and these are connected with wires, nerves, or conductors, which pass on the stimulus to the areas of muscular activity. There may be threshold-resistances to be overcome so that undue impetuosity of response is avoided ; there are arrange- ments for the summation of stimuli, for laying down paths so that action-patterns are formed ; and all has a phylogenetic reference, that is to say, neuro-muscular pre-arrangements work well to-day because all has been wrought out through the ages in reference to frequently recurrent problems. It is hardly possible to exaggerate the nicety of adaptiveness the brain is the storage battery, the muscles the seat of motor activity, the liver makes fuel and helps to remove ashes, the thyroid gland effects speed control, the adrenal body has to do with counteracting the accumulation of acid waste-products, and so on through the inter-dependent series of organs which make up the kinetic system of the body. What need is there for mind ? Is it more than a name for ' versatility of nervous response ' ? In an admirable exposition of Man as an Adaptive Mechanism, Professor Crile shows how much the human body is good for without any help from the human mind. It is strange, however, that one of his notable advances in surgery is associated with the recognition of the importance of fear or anticipation before operations, and we cannot 522 THE EVOLUTION OF MIND agree that fear or anticipation is adequately accounted for in terms of physiology. Another strange thing is that Pro- fessor Crile includes among the functions of his adaptive mechanism " the fabrication of thought ". One might say that it was not a good thought that Professor Crile's mechanism fabricated when it conceived of the organism as a mechanism; but his position is theoretically impossible a contradiction in terms. The apsychic formulation seems unsound practically as well as theoretically. On the theory that mind does not count, we may make much of a horse or a dog, but certainly not most. There is a great deal of sound sense, we think, in the quaint words of one of the old breeders, Gervase Markham (1621): " You shall beginne to handle and in- struct your dogge at four months old; . . . make him most loving and familiar with you, taking a delight in your com- pany, also mix with this familiarity a kindly awe and obe- dience which you shall procure rather by tenderness than by terrefying him, which only maketh him sly/' It is wrong " ever to hurry your young dogge, give him time to fix himself and much liberty of movement, handle him firmly but tenderly." (Quoted by Dr. N. C. MacNamara in his Instinct and Intelligence, 1915, p. 183.) There are two fallacies in the doctrine of the uselessness of mind. In the first place, it ignores the fact that the process of organisation (otherwise called automatisation and still more unfortunately mechanisation) has the effect of increas- ing efficiency at a higher level. It enables the creature to meet novel circumstances, to experiment, to make a purpose- ful use of its own experience, which is what we call intelli- gence. Just as in our own life we practise labour-saving, time-saving, worry-saving methodical devices, so as to have MIND IN EVOLUTION 523 our mind more free for its own adventures, so the consum- mate registration that the organism exhibits is a device for the emancipation of mind. The second fallacy is the assumption that what now takes place reflexly, tropistically, or instinctively never required mental control. Without accepting the theory that reflexes have been organised by habituation, we may recall such experiences as learning to ride a bicycle, which show how extraordinarily automatic movements' may become which originally required all our attention and a good deal of strong will. In cases like playing the violin the original efforts often require a good deal of intelligence, for those learn best who see clearly the relation of means to end. Of reflexes, Professor Sherrington writes (p. 388) : " Per- fected during the course of age part of the in- heritance may remain entirely unexpressed in the individual development because certain environmental conditions are lacking, yet the heritable character may be handed on all the same. Thus fruit-flies (Drosophila) of a Mendelian race with a peculiar abnormality may appear perfectly nor- mal if raised in a dry environment, but the presence within them of the ' factor ' for the abnormal feature may be demonstrated by rearing their offspring in a damp place. This shows the importance of nurture for the individual. A diagrammatic illustration concerns the red Chinese primrose (Primula sinensis rubra). Reared at 15 20 C. it has red flowers. Reared at 30 35 C., with moisture and shade the same plants have pure white flowers like those of Primula sinensis alba, which always has white flowers. Thus we see that the development of colour in the red Chinese primrose depends on its nurture. Take another illustration from the fruit-fly. There is a mutant stock that produces supernumerary legs, in consider- able percentage in winter, few or none in summer. Miss Hoge finds that when the flies are kept in an ice-chest at a temperature of about 10 C., a high percentage of individ- uals with supernumerary legs occurs. In a hot climate there would be no evidence that the peculiarity was part of the inheritance; in a cold country it would be obvious. This shows that the expression of the inheritance as regards a particular character sometimes depends on nurture. In estimating the importance of nurture for the individ- ual man, we must remember how largely the human mind is a social product. As Prof. George H. Parker (1914) puts it, " Our intellectual outfit comes to us more in the nature of a social contribution than an organic one." Per- LESSONS OF EVOLUTION 611 haps it is going too far to suggest that as regards our minds we are more i made ' than ' born ' ; but this is certain, that while our mental capacities are primarily determined by heredity, they can be encouraged and augmented, or in- hibited and depressed, within wide limits, by nurture. On no account are we to countenance, if we can help it, spoiling good stock by bad, for that is the worst thing man can do. But we must beware of confusing veneer with hereditary nature. We must not too readily assume that people are as good as they look, or as bad as they look. In regard to the last, in an interesting study entitled Environ- ment and Efficiency, Miss Mary Homer Thomson tells of her investigation of 265 children, mostly of " the lowest class" (Class A, fourth below the poverty level!), who had been sent to institutions and trained. She found that 192 (72 per cent.) turned out well; that 44 (16 per cent.) were doubtful; and that only 29 (less than 11 per cent.) were unsatisfactory, and of these 13 were defective. These fig- ures, which should of course be checked and extended, afford some evidence of the controllability of the individual life. Less extremely than some other Mendelians, Professor Punnett writes : " Hygiene and education are influences which can in some measure check the operation of one factor and encourage the operation of another. But that they can add a factor for a good quality or take away a factor for an evil one is utterly opposed to all that is known of the facts of heredity." But a practical note may be here permitted. It is very difficult for us to know all that is in a man's inheritance. Indeed we cannot, for we can see only what is expressed, and the condition of expression is appropriate nurture. 612 THE CONTROL OF LIFE: Therefore in Man's formative periods the common-sense view is surely this. We cannot he quite sure what we have in our inheritance, therefore let us give every chance to such qualities as are liberated by ameliorative nurture. We can- not be quite sure what may not be in our inheritance, there- fore we take no chances ; let us avoid the kind of nurture that arouses sleeping dogs. The theory of the control of life is here quite plain : the practice, we admit, is no easier than be- fore, save that we understand the issues better. 4. Selection the Third Determinant of Life. The third determinant of life is Selection, and this is of peculiar importance in the human sphere, where Natural Selection is largely in abeyance and the sifting is in great part rational and social. We call it rational and social because it is more or less deliberate and thought-out and because it is effected by social sieves; unfortunately this does not mean that it may not be terribly mistaken. In early days mankind was much in the sieve of Natural Selec- tion the meshes being wild beasts, changes of climate, scarcity of food, unchecked disease, and so on, and we are the better for that sifting to-day. But, as every one knows, the whole trend of human evolution since civilisation began has been to throw off the yoke of natural selection. Some of its thraldom remains, as in cases of differential death- rate, where the inherently weaker succumb in larger num- bers, but we are continually interfering necessarily and rightly with the sifting operations of disease, hard -times, and the like. This interference has been in great' part prompted by the strengthening and diffusion of the humaner sentiments and a realisation of our solidarity ; but it involves, as every one recognises more or less clearly, the terrible danger LESSONS OF EVOLUTION 613 of relaxed sifting. In regard to that the records of organic and social evolution are alike eloquent. No one has stated the dilemma more poignantly than Spencer : " Any arrange- ments which, in a considerable degree, prevent superiority from profiting by the rewards of superiority, or shield in- feriority from the evils it entails any arrangements which tend to make it as well to be inferior as to be superior, are arrangements diametrically opposed to the progress of or- ganisation, and the reaching of a higher life." That way perdition lies. It is a dilemma of civilisation that we can- not tolerate Nature's regime, the individual life means so much to us ; and yet we have not replaced it by any suffi- ciently strict, and consistent, and carefully thought-out sift- ing methods of our own. There is satisfaction in healing the sick and preventing wastage of life; we cannot but try to alleviate suffering; but there is no gainsaying the danger of being cruel to fu- ture generations by being kind in the present. There is the undeniable risk of helping too much, of coddling the un- desirable and unwholesome so that they get strength enough to multiply, often spoiling good stock with the infiltration of bad. The wheat may have too much sympathy for the tares, and societies for the amalgamation of heaven and hell do not commend themselves to the wise. This is a large and difficult question the transition from Natural Selection to some other kind of selection which will grip the germ-plasm. The following three considerations are submitted. (1) In a number of cases the diseases and miseries with which civilised man is successfully coping are indiscriminate in their elimination. They thin the ranks, but they do not weed out or sift. The checking of such diseases and miseries will not, therefore, especially encourage 614 THE CONTROL OF LIFE: the survival of types who are a source of weakness to human society. Hygienic endeavours which interfere with indis- criminate elimination as in the case of much infantile mortality may be pushed on unhesitatingly. (2) As things are, there ought to be no question of drastic social surgery or of accepting Plato's proposals for the purga- tion of the state. For, on the one hand, we do not know enough to go far with safety, and, on the other hand, we are forbidden by the social sentiment of the most moralised types. What can be done is to work back to the old and wholesome pride of race, and to work away from whatever tends to encourage the multiplication of the diseased and the unwholesome. For a long time to come reformers will have enough to do along negative lines, in seeking to prevent the spoiling of good stock with bad. Much may also be achieved by educating public opinion, replacing baseless prejudices by convictions founded on facts. It is not in the 20th cen- tury too much to ask that the quaint lists of forbidden degrees which used to be prefixed to copies of the Scriptures should be replaced by sound eugenic information. (3) The commonplace must be borne in mind that man is a social person, and that what is biologically commendable may be socially disruptive. Many of those who are seriously handicapped by inheritance, and who ought not to be en- couraged to have offspring, are in other respects valuable citizens. Many of the weaklings whom the social surgeon threatens are strong in spirit. As poets and artists, reform- ers and preachers, many of the weaklings have been among the " makers and shakers ' of the world. A useful office is the careful criticism of all the methods of discriminate elimination whether deliberate or not that are at work in mankind. Some economists have wisely LESSONS OF EVOLUTION 615 urged upon us the importance of criticism of consumption, for it is plain that in our expenditure we are willy-nilly selective. Thus a tradition of consistent expenditure along restricted materialistic lines must make for the elimination of artists, musicians, and similar types who are the salt of the earth. It condemns them to celibacy ; it lets them slowly starve. Considerations of this sort may be exaggerated so as to make life a burden too heavy to be borne, but it is plain that a community which is spending solely on things that perish in the using cannot be on a sound line of evolution. All expenditure that consistently promotes unhealthy oc- cupations rather than healthy ones, that helps to foster and multiply the feckless rather than controlled types, that makes for sweated labour and slums rather than for well-paid work and gardens, is necessarily anti-evolutionary. From founding celibate fellowships at colleges down to advertising for gardeners " without encumbrances ", every form of selec- tion that tends to prevent good types from duly contributing to the composition of succeeding generations is to be con- demned in the court of applied biology, often called eugenics. That there may be a higher court of appeal is not denied. An outstanding fact of Animate Evolution is, that new departures making for the welfare of the race become in- grained and entailed as part of the adaptive organisation of the creature. In the case of Man there has been a similar enregistration ; it is idle to deny that there has been a heredi- tary organisation of kindliness, helpfulness, cheerfulness, and so on. But this hereditary organisation proceeds slowly, and so we must trust greatly to the extra-organismal heritage of traditions, conventions, ideals, and the like which works very potently both as a stimulating nurture, prompting us 616 THE CONTROL OF LIFE: to seek after virtue and understanding, and also as a selec- tive agency, leaving us behind if we fail too utterly of what society expects of its members. In education intellectual, physical, and moral we do of course habitually seek to utilise nurture in the widest sense which includes the social heritage as a means towards making the most of the individual development, and what, it may be asked, have we to offer in the way of new sugges- tion ? Simply this, that we might to advantage be more scientific and less vague; that we should utilise with resolute- ness and conviction the suggestions which expert science has to offer in regard to manifold problems in the control of life. We are convinced that many of the so-called " cosmic shadows ", such as the wastefulness of Nature, are misunder- standings ; we are convinced that many of the shadows of human life are gratuitous, that they would be scattered if we let in more of the light of science. Our forefathers had to deal with these shadows in an indirect way or not at all; often the only thing to do was to try to get moral discipline out of them. But now we have made great advances towards understanding many of the human shadows, and it is only inertia that keeps us from directly dispelling them. Much is being done every day, but much more requires to be done, and our point is that the first and foremost lesson of evolu- tion is: Let in more light, more scientific light. Another lesson, of course, is: Let in more Love. We know that a normal development of the human or- ganism in mind and body demands an appropriate nur- ture; and yet we are implicated in human environments which are not up to the normal standard. In these environ- ments, which make us ashamed, good men and women do indeed live, but there are surely many of the dwellers in LESSONS OF EVOLUTION 617 darkness who find the great task of happiness altogether too hard. Similarly, in regard to functional fatigue, there is a very considerable body of experimental fact in regard to the profitable length of a school-lesson, the profitable length of a school-day, the profitable length of a working-day, but how slow we are to utilise expert advice. In regard to occupational fatigue it is well known that it is the last straw that breaks the camel's back, and that what gives a push towards the danger-zone is often the entirely remediable delay in procur- ing appetising food. These are familiar instances which we use simply as dia- grams of the sad fact that we have got so accustomed to fold- ing the hands when we did not know what to do, that we continue our resigned acquiescence even when the path of effective action is clear. Professor Ward has spoken warmly of what man may achieve by an increased control of life (Realms of Ends, p. 112). " What the schoolmaster, the physician, and the phi- lanthropist effect for the amelioration of the masses needs no description. Here again we have definite direction over- riding the random and untrained impulses of the natural man. While the progress already made in the physical and social ameloriation of human life is inestimable, it is as noth- ing compared with what is still possible. Nine-tenths of our physical ills are due to ignorance and perhaps a still greater proportion of our social evils are due to selfishness. Present scientific knowledge is adequate to remedy a very large proportion of the former, and the ordinary prudential maxims of utilitarian morality, if they were only observed as they might be, would go far towards extinguishing the latter: they would put an end to the worships of Venus, 618 THE CONTROL OF LIFE: Bacchus, and Mammon, if even they did not establish peace and chain up the dogs of war for ever." This was 1907- 1910. In the cases where the issue is relatively clear we have of course made great progress. We think of malaria and Malta fever, of diphtheria and plague, and many other diseases now coming under control. Not many years ago a number of religious and worthy Boer farmers uncon- sciously impious refused to join with an effective Anti- Locust League which depended for success on concerted action; they gave for their reason that it was attempting to stay the hand of God. But already this sounds like an- cient history. Not in regard to diseases and pests alone, but in regard to depressing environment, ugliness, and dirt; in regard to dangerous and deteriorative occupations; in regard to poverty and unemployment, and, in short, all manner of objective evils, we have a determination rapidly growing stronger in our midst to get at the facts, to understand the operative factors, and to put brains into the task of better- ment. Knowledge is foresight, and foresight is power. Science is for the ameloriation and control, as well as for the enlightenment of life. To have this conviction strongly is surely to show no profane depreciation of the things of the spirit which are beyond the scientific universe of discourse. It is the complaint of most of us that scientific efforts for the alleviation of misery and the scattering of gratuitous shadows move so very slowly. On the other hand, there is some reason to be afraid of movements that make people more comfortable without making them more ambitious in the quest for the True, the Beautiful, and the Good ; and of reforms which save guilty people from the consequences of sin, selfishness, and sloth. LESSONS OF EVOLUTION 619 5. Importance of Correlating Organismal, Functional, and Environmental Betterment. A consideration of organic evolution suggests that pro- gressive change depends on the correlation of functional and environmental with organismal improvement. We see writ large the lesson that a promising organisation may undergo involution in conditions of ease and safety, that the parasite is branded by degeneration, that unused organs dwindle away. We have seen that the development of characters is in some measure dependent on nurture, that progressive variations are apt to be short-lived unless the environment be also pro- gressive, that the sifting is always in relation to a definite here and now namely, the surrounding web of life in which some of the great advances of the past are always in some measure systematised. What is true of organic progress is yet more abundantly true of human progress, physical and social, as well as organic: that there must be a correlation of three kinds of endeavour, that which aims at the im- provement of the organism or breed (Eugenics), that which concerns itself with the ameloriation of the environment (Eutopias or Euthenics), and that which seeks to bring about the betterment of functions, especially occupations (Eu- technics). Different sides of progress appeal to different minds, and few of us can work effectively at more than one thing at a time, but perhaps we should give greater prom- inence than we do to the simple lesson of Evolution that lasting betterment must be realised in place and work as well as in people, in environment and function (including leisure-time activity) as well as in organism. 620 THE CONTROL OF LIFE: 6. Dangers of False Simplicity or Materialism. When we turn to the consideration of practical problems, we reap the reward of the time devoted to the discussion of the essential characters of the living organism. The con- clusion that the category ' Mechanism ' requires in Animate Nature to be supplemented by the category ( Organism ', warrants us in carefully scrutinising all proposals which are tarred with the mechanistic or materialistic brush. They are bound to be fallacious in their incompleteness and per- haps also in the clear-cut definiteness which makes false sim- plicity seductive. The conclusion that, among the higher animals at least, we have certainly to do with mind-bodies or body-minds, with individualities having at least a rill of inner life, justi- fies us in looking with suspicion at projects which declare the uselessness of the soul. The " false simplicity " error of materialism may be repeated at a higher level in a biologism which leaves out mentality in its account and treatment of a dog, or in a theromorphism which treats men as " bipedal cattle " often of considerable ferocity. It is not merely a theoretical question of giving the most accurate description of a dog or a horse or a man, it is also a practical question of making the most and the best of the creature. And in this respect the conclusion of thoughtful experts is unanimous, that the truer conception is also that which works best. There are many higher reasons (religious, ethical, artistic, and others) for taking a big view of Man, but what we have been concerned with in this course is to show that the crude view is bad science. When Prof. Jacques Loeb says, " We eat, drink, and reproduce, not because mankind has reached LESSONS OF EVOLUTION 621 an agreement that this is desirable, but because, machine- like, we are compelled to do so ", he does not make a good antithesis. It is a familiar fact that Man often inhibits these organised impulses, and does so in reference to ideals which mankind has built up in a manner almost as far from the average animal's ways as these are from a machine's. When Le Dantec says, " The fact of being con- scious does not intervene in the slightest degree in directing vital movements ", we think that he is departing from the first canon of scientific work accuracy. Often in man's experience it is just the being conscious that makes all the difference. It may be useful to give two or three examples to show that proposals fundamentally biological need not be narrow or materialistic. Many authorities on education have em- phasised on various grounds the importance of Play, but discussion passed to a firmer basis after the important work of Groos on the play of animals, for he showed that play was no mere safety-valve for superabundant energy and spirits, no mere relaxation, no mere recapitulation, but that it was a joyous apprenticeship to the business of life, a time for replacing instinctive predispositions by learning from experience, a time of elbow-room for variations, a time for experimenting before criticisms prune, before casu- alties induce caution, and before hard work brings on " life- harming heaviness." Or again, it may be well for us, on our own behalf and for our children, to ask whether we are making what we might of the well-springs of joy in the world ; and whether we have begun to know what we ought to know regarding the Biology or Psycho-biology of Joy. Have we given atten- tion, for instance, to the work of the famous physiologist 622 THE CONTROL OF LIFE: of Petrograd, Prof. Ivan Petrovich Pavlov, who was the first to demonstrate the influence of the emotions on the health of the body ? That a good circulation is associated with cheerfulness is a familiar fact, and how this organic jauntiness sometimes jars on the tired and sorrowful! But there is the converse proposition that cheerfulness makes for health. It was said of old time : " he that is of a merry heart hath a continual feast ", and " a merry heart is the life of the flesh ". Now, what the researches of Pavlov, Cannon, Carlson, Crile, and others have done is to demon- strate experimentally that pleasant emotions favour the secretion of the digestive juices, the rhythmic movements of the food-canal, and the absorption of the aliment. Con- trariwise, unpleasant emotional disturbance and worry of all sorts have been proved to have a retardative influence on the digestive processes. When the hungry man sees the well-laid table his mouth waters, but every one knows that a memory or an anticipation will also serve to move at least the first link in the digestive chain. " It is now well known/' says Professor Dearborn, " that no sense-experi- ence is too remote from the innervations of digestion to be taken into its associations, and serve as a stimulus of diges- tive movements and secretions." Emotion may influence the production of adrenalin by the core of the adrenal glands, and a slight increase in this potent substance constricts the smaller blood-vessels, raises the blood pressure, excites and freshens the muscles, increases the sugar content of the blood, and so on. From the non-mechanistic position which we have defended in these lectures, it is of great interest and importance that good news, psychical if anything is, may set in motion a series of physico-chemical and vital processes, complex beyond the ken of the wisest. And the LESSONS OF EVOLUTION 623 cheerful man, who cultivates the habit of happiness, finding good reasons for rejoicing in the sunshine and stars, in flowers and birds, in works of art and the faces of his friends will have his ' joy-reward ' or euphoria added unto him unless he is fool enough to pursue it. Our point is, that, open to at least a large number of our fellow-creatures, there are sights and sounds that make for joy and that increas- ingly, as some of the Psalmists were well aware, and that one of the obvious lessons of evolution and of common sense is that we should use these well-springs freely. What is true in regard to digestion applies also to other functions. Wordsworth knew this when he spoke of his heart responding to the sight of the rainbow and the recollec- tion of the daffodils by the lakeside. He may not have known much about the complex pathways of the pneumo- gastric, but he was sure about the influence of joy on the cir- culation. Professor Dearborn has worked at the factors alter- ing blood-pressure and he makes the notable statement that in the " general stimulation of the essential circulation in all constructive parts of the body, such as the brain, the muscles, and the digestive organs, joy exerts one of its most conspicuous benefits, and one that no one can doubt or ignore ". There are facts which point to the conclusion that a glad- some mind may also increase the integrative function of the nervous system. It is an indubitable fact that a joy say of maternity, or discovery, or artistic creation may become an exhilaration and enthusiasm of thought and will ; but the same is true of bodily welfare. Good tidings will invigorate the flagging energies of a band of explorers ; an unexpected visit will change a wearied homesick child, as if by magic, into a dancing gladsome elf; a religious joy 624 THE CONTROL OF LIFE: will make men and women transcend the ordinary limits of our frail humanity. How it comes about is not yet quite clear; but somehow the oil of joy, as the Scriptures call it, operates so as to make the limbs more supple and the face to shine. Emotion has its physical accompaniment in motions throughout the body, in changes in secretion and circulation, and also in some other way whereby influences from some emotional ' centre ' such, perhaps, as the optic thalamus (the second great division of the brain) surge up into the cerebral cortex, the seat of the higher mental proc- esses, where joy and activity may be correlated. We have referred to recent work on the physiology of joy simply as an illustration of the way in which science may be utilised in the control of life not merely as regards ex- ercise, fresh air, diet, and so on, but in the subtler task of developing the personality on what one may call direct lines. The danger ahead is well known, that, just as the direct pursuit of health is apt to engender hypochondria and vale- tudinarianism, and just as the direct pursuit of happiness is apt to defeat its own end, so the direct pursuit of joy for the sake of the ' joy-reward ' may prove consummately futile. But it is possible to make a bogey of this risk. We are not made of such friable material. Forced cheerfulness is, of course, a horror, but the per- sistent will to be glad, if worthily satisfied with some of the real joys of life, may soon become a habit that requires no artificial stimulation. A conventional approach to Nature and Art is often rewarded much beyond its deserts, and men who began by taking walks for duty's sake have often become genuine enthusiasts for the open country. The pur- suit of joy may be futile and the faking of it an abomina- LESSONS OF EVOLUTION 625 tion, but there is nothing absurd or morbid, for instance, in humbly learning to know more about the endless things of beauty which are joys for ever. If we make sure of these, the euphoria will look after itself. It is surely for the guidance of youth to recognise that at levels far below Man's there is an enhancing of physical fondness by aesthetic embroideries and emotional tenderness, and the sobering of all by a working together of mates in the discharge of parental duties. It is surely for the guidance of all to realise the extent to which animal life rises above a struggle around the platter of subsistence, and illustrates the raw material, at least, of domestic virtues. We cannot believe that animals " think the ought ", so that in the strict sense the ethical note is not sounded, but when we consider their expenditure of energy towards results that are other-regarding not self-regarding, we seem to hear an ethical undertone. In any case it is not from Natural History that we learn the " Might is Right ' doctrine. 7. Science for Life. Let us sum up the general argument. (1) There is no doubt whatever that many of the human shadows that blot out the sun and make our feet stumble are gratuitous, and may be got rid of whenever man pleases. That this condition, " whenever man pleases ", is not easily fulfilled we are well aware. But there is no doubt that we can get rid of many social handicaps, and go on to higher adventures, discovering more and more of the goodness of God in the land of the living. A hundred years ago people shuddered at the name ' Gaol- fever ', a terrible pestilence, which attacked judge and jury, 626 THE CONTROL OF LIFE: prisoner and onlooker at Old Bailey. We call it typhus-fever now, and it is rare in Britain, thanks to the enthusiasm of the early nineteenth-century hygienists. It is a dirt disease, it can be controlled by care and cleanliness. It is due to a microbe, not yet isolated, which is transferred from man to man by infected lice. As Sir Ray Lankester says, the Angel of Death they spoke of a hundred years ago is the clothes' louse, which can be readily exterminated by the use of benzine. We cannot but feel that it was almost con- temptible to have submitted for centuries to a tyranny of dirt; but the point is that we are continuing to submit to similar things. We are slow to gird up our loins. We are slow to learn the lesson of the Control of Life. (2) It has been said that there are two views of this world, that which regards it as a swamp to be crossed as quickly as possible, and that which regards it as a marsh to be drained. The view to which our study of Animate Nature points is emphatically the latter. Man must continue the struggle against inhibitants, the campaign in which living creatures have been engaged for millions of years, the endeavour to bring the inorganic into the service of the organic, to bring the body-mind into subordination to the mind-body, to eliminate the disorderly, the inharmonious, the involutionary. For we adhere to the thesis that evolution is on the whole integrative, not disintegrative. (3) To put the same thing in a third way, which is more generalised, we are in profound agreement with the view well expressed by a contemporary philosopher, that it is Man's part to build up, as he is doing, a scientific systemati- sation of knowledge which will form the basis of an in- creasing control of life. The mundane goal of the evolution- ary movement is " the mastery by the human mind of the LESSONS OF EVOLUTION 627 conditions, internal as well as external, of its life and growth. The primitive intelligence is useful to the organism as a more elastic method of adjusting itself to its environment. As the mental powers develop, the tables are turned, and the mind adjusts its environment to its own needs. ' Mihi res non me rebus subjungere conor ' is the motto that it takes for its own. With the mastery of external nature, ap- plied science has made us all familiar. But the last enemy that man shall overcome is himself. The internal conditions of life, the physiological basis of mental activity, the socio- logical laws that operate for the most part unconsciously, are parts of the ' environment ' which the self-conscious in- telligence has to master, and it is on this mastery that the regnum hominis will rest' (Hobhouse, 1915, p. 443). Of a truth, Science is for Life, not Life for Science. SUMMARY. The theoretical doctrine of evolution has for its practical corollary the fact of the controllability of life. Darwin was logically fol- lowed by Pasteur. If the central fact in evolution be " the slowly wrought-out dom- inance of mind in things ", it is surely man's fundamental task to use this expanding mind for the fuller possession of his kingdom, and the better ordering of his life in it. If evolution suggests any les- son it is this. We must inquire, therefore, into the determinants of life. The first determinant of life is heredity our relation to preceding generations which includes not only the past living on in the present, but new departures or variations. We cannot alter our own inheritance, though it is ours to trade with, but we have some meas- ure of control over the inheritance of future generations. The second determinant of life is nurture all manner of for- mative influences from surroundings and from use and disuse and this is largely controllable in our hands. Nurture determines the fulness of expression that hereditary characters may attain in 628 THE CONTROL OF LIFE development; it may re-impress desirable modifications on succes- sive generations; it determines in part the sort of reception a new variation meets with. In mankind ' nurture ' includes the ' social heritage \ The third determinant of life is selection, and this is of peculiar importance in mankind, where natural sifting is largely in abey- ance, where the sifting is in great part deliberate, rational, social. The relaxation of natural selection is the inevitable result of the increase of solidarity and sympathy; the difficulty is to find a sufficiently stern substitute. It should be noted that humane inter- ference with indiscriminate elimination (which thins without sifting) cannot harm the race; that drastic social surgery is impossible in the present state of science and social sentiment; and that proposals which are sound biologically may be disruptive socially. A study of animate evolution points to the conclusion that secure progress implies a correlation of organismal, functional, and envi- ronmental improvements. This is even more true as regards progress in the kingdom of man. The hard-won conclusions that in Animate Nature the category ' mechanism ' requires to be supplemented by the category ' or- ganism ', and that among the higher animals at least this requires to be supplemented by the conception of ( mind-body ' (and in mankind by that of social personality), afford a test for practical projects. The error of materialism (namely, false simplicity) is often repeated at a higher level in biologism and theromorphism. The error is not in theory only, but shows itself in practice when the problem is to get the most or the best out of the creature. It is very interesting to consider the extent to which animal life rises beyond a struggle around the platter of subsistence, and illus- trates the raw material, at least, of domestic and social virtues. In the strict sense it may be true that the ethical note is not sounded, but there is often an ethical undertone. Nature has stamped this with her approval, Huxley notwithstanding. LECTURE XX. VIS MEDICATKIX NATTIER. LECTUKE XX. VIS MEDICATEIX NATUB^E. 1. Biological Aspects of the Healing Power of Nature. 2. Psychological Aspects of the Healing Power of Nature. 3. Correspondence in Animate Nature to our Ideals of the True, the Beautiful, and the Good. 4. Humanist Value of the Study of Animate Evolution. 5. Scientific Description of Animate Nature Not Inconsistent with Religious Interpretation. 1. Biological Aspects of the Healing Power of Nature. IN many different ways Man has realised the healing power of Nature vis medicatrix Naturae and all of them are instructive. One might refer, for instance, to the heal- ing virtues in many natural substances, both animal and vegetable, some of which are extraordinarily quaint. It has been re-discovered in modern times that more than one snake carries in its gall-bladder a sure antidote to its own venom. Is not the old advice that the coward should eat of the heart of a lion, so that he might be brave, echoed in the modern treatment of a cretinoid child with the thyroid gland of a sheep ? Is it not like a leaf out of an old book of magic to read that an enlightened use of pituitary extract enabled a successful examinee to add in a short time to his height the couple of inches that were required in order to secure a post for which he had proved himself otherwise eligible? It looks as if by taking sufficient thought one might be able to add a cubit to one's stature. Interesting too is the reparatory power exhibited by many living creatures. One of the Big Trees or Sequoias which 631 632 VIS MEDICATRIX NATURAE was a seedling in 271 B.C., suffered a burn three feet wide when it was 516 years old, and spent 105 years in folding its living tissues over the wound. When it was killed at the age of 2,171 years, a Methuselah among trees, it was engaged in healing a third great wound 18 feet wide and about 30 feet high. Vis medicatrix Natures. A sponge can be cut up and planted out like a piece of potato-tuber; it may be minced and pressed through a cloth sieve without losing its power of regrowth. An earthworm thinks nothing of regrowing a new head or a new tail, or a snail its horn and the eye at the tip, even unto forty times. And this regenerative capacity is in the main adaptive in its distribution, for, as Lessona and Weismann have shown, it tends to occur in those animals and in those parts of animals which are in the natural conditions of their life peculiarly liable to non-fatal injury. Long-legged and lanky animals like crabs and starfishes usually show much of it; a self-contained globular animal like a sea-urchin shows little. The chameleon is one of the few lizards that does not regrow a lost tail, for, as it keeps it safely coiled around the branch, the regenerative capacity has fallen into abeyance. Many other instances might be given of Nature's healing power: the processes of rejuvenescence which in many or- ganisms are continually at work in staving off senescence; the natural defences of organisms, such as the bodyguard of migratory phagocytes which deal with intruding microbes, and the mysterious intrinsic counter-actives or anti-bodies which deal with toxins ; the immunity which some animals have to poisons, as the mongoose to snake-bite ; the regulatory processes which sometimes occur when development or nor- mal function is disturbed ; the absence of disease and senility in wild life; the way in which some simple animals evade VIS MEDICATRIX NATURE 633 natural death altogether; the numberless arrangements for keeping the earth clean and sweet; the hygienic value of sunshine and fresh air. These matters lie outside our proper theme, but they are well worthy of being recalled. Even when one is able to give a reasonable account of how they have come to be, they illustrate the balance and adaptiveness which is charac- teristic of Animate Nature. Only a system with order and progress in the heart of it could elaborate itself so perfectly and so intricately. There is assuredly much to incline us to " assert Eternal Providence, and justify the ways of God to Men ". 2. Psychological Aspects of the Healing Power of Nature. Let us think, however, of the way in which Nature con- tributes to the hygiene and healing of our minds, so apt to be disturbed by the rush and racket of civilisation. There are deeply-rooted, old-established, far-reaching relations be- tween Man and Nature which cannot be ignored without loss. Man was cradled and brought up in touch with Na- ture, and he must ever return to her, like the wandering birds whose life is never full until, moved by an organic homesickness, they come back to nest in the place where they were born. In a period of evolution which has been mainly urban, we miss our contact with the open country, which is, for many, a condition of full sanity, and makes for the steadying and enrichment of life. Especially in youth is touch with Nature invaluable, for it remains true of the child who goes forth every day that " what he sees becomes part of him for a day, or for a year, or for stretching cycles of years ". It seems a pity that the modern child is often unfamiliar with the Scriptures; 634 VIS MEDICATRIX NATURE it is also to be deplored that he is often equally unfamiliar with the book of Nature. Man needs to sojourn with Nature in order to get certain fundamental impressions without which he is impoverished, the impressions from the starry sky, the pathless sea, the mountain-top, the dense forest, the apple-blossom, the ant- hill, the swallows flying south in autumn. Man cannot safely dispense with the fundamental impressions of power, of large- ness, of pervading order, of omnipresent beauty, of universal flux, of intricacy, of growth, of the web of life, of adaptive- ness, of evolution. Some minds weary of theories ; let them by sympathetic observation hug the facts close, for thus also may deeper visions of reality be gained. Let them by ob- servation draw water from what an expert naturalist has called " the bottomless well of surprises ' (Chalmers Mitchell, Finite Life and Individuality, p. 60). Another healing virtue in Nature is to be found in its perennial problem-setting interest. It arouses our attention ; it intrigues the curious spirit; it leads us on and on like the tales of the Thousand and One Nights. As some one said, it is like a serial story. Its study is a brain-stretching exercise, and while it rewards the discoverer with both light and power, it subjects him to a discipline which engenders humility. For is not all our science rounded with mystery mystery as to essences, mystery as to origins, mystery as to mutations. What we are surest of is the fundamental mysteriousness of Nature. 3. Correspondence in Animate Nature to our Ideals of the True, the Beautiful, and the Good. There is a legitimate scientific sense in which it may be said that Man is not only a part, but a product of the system VIS MEDICATRIX NATURE 635 of things and creatures that we call Nature. We know, in- deed, that the system in its subjective expression is of Man's making; we know also that Man was made by the system. This is a familiar riddle. Needless to say, however, the system cannot mean to us a mindless kaleidoscope, for by no jugglery can one evolve mind out of anything else. But keeping to the common-sense view that Man is of a piece with a real external Nature, though transcending it when he will, we are concerned to point out that Nature is not altogether so foreign to Man as is continually insinuated. The highest values for Man are the True, the Beautiful, and the Good ; and it is of interest that there are in Nature features which do in some degree correspond to these. For it is not far-fetched to recognise that there is a rationality in Nature which is there to be discovered or discerned, which is not simply imposed upon Nature by our formulation. In what sense can we speak of a rationality in Nature ? We mean that the system of things is more or less intelligible and explicable, that its relative uniformities can be trusted to, that when we get a grip of things we can make a coherent scientific system of them, which fits in with other parts of our intellectual systematisation. The formulation is some- times premature and forced, but this is discovered in time, for Nature does not humour the inquirer. The Ptolemaic system in astronomy had to yield to the Copernican, that to the Keplerian, that to the Newtonian, and so on, but each advance meant getting nearer the truth, as we know by the increase in consistency on the one hand, and by the increase in the astronomer's power of prediction on the other. This would not be possible did not scientific formulation approximate towards a description of what actually happens. That Nature is amenable to scientific formulation dis- 636 VIS MEDICATRIX NATURAE cerned rather than imposed upon it is admitted by all, but the interpretation is as difficult as the fact is obvious. It is a philosophical problem, but a scientific note may be per- mitted. To be asked how the marvellous fabric of science, one of the greatest human achievements, is to be explained in terms of evolutionary formulae, is like being asked to account for the evolution of some very complex and relatively perfect structure like the human eye. Such questions have to be treated historically. Science and the eye must be looked at as the results of long processes of evolution, vastly older than Man. We trace the eye back to simple clusters of sensory cells, and we trace science back to simple practical lore, and further back still to pre-human capacities of* learn- ing. The acquisition and the expansion of the early lore had assuredly survival value; inborn curiosity has been from first to last a stimulus to inquiry; registration of gains in language and reeords, in instruments and permanent products, has made compound-interest advance possible. The result is not less admirable because its early stages were humble; but to ignore the early stages is to make the Ascent of Man magical. But this does no more than give setting to the metaphysi- cal problem. The strands of naturally-determined sequence have woven themselves into an intelligible pattern which science discerns; is it conceivable that they might have tied themselves into a knot baffling all disentanglement? And we must remember that almost all the discernment of the order of Nature has depended on seeing the stars in un- beclouded skies. Various attempts, such as Lachelier's (1871), have been made to explain the 'correspondence' between the intrinsic order of Nature and Man's capacity for deciphering it, but it seems doubtful if we get beyond VIS MEDICATRIX NATURE 637 some device which dissolves rather than solves the problem. It looks like a frontier-problem for Man's intellect. But, leaving this puzzle, do we not find some quiet for our unrest in the progressive disclosure of the orderliness of Nature? Ours is no phantasmagoria of a world, but a Systema Naturae. We are parts of a reasonable world, which voices reason and listens to reason. Its process has worked persistently towards masterpieces, of which the climax is the reasonable soul. From the intrinsic order and intelligibility of Nature, which the rise of the magnificent scientific edifice proves, we may not be logically permitted to make a tran- scendent inference to an Omniscient Creator, but it is in that way the heart of Man points. Our belief is that the Logos is at the core of our system, implicit in the nebula, as no"w in the dew-drop. It slept for the most part through the evolution of plants and coral-like animals, whose dream- smiles are a joy for ever. It slept as the child sleeps before birth. It became more and more awake among higher ani- mals, feeling and knowing and willing. It became articu- late in self-conscious Man, and not least in his science. Scientific re-constructions are not arbitrary projections, for they work. In this sense there is rationality in Nature. But if there is rationality in Nature, must we not go fur- ther ? For, as Aliotta has put it, " He who believes in the objective value of his science must then also believe in God. If an absolute thought does not exist, Nature cannot be rational ". Descartes rested his belief in Science on his belief in God. In his Gifford Lectures Mr. Arthur Balfour rested the belief in God on a belief in science, for " God is himself the condition of scientific knowledge ". To some it may seem far-fetched to find in Animate Nature a correspondence to Man's truth-seeking. But we 638 VIS MEDICATRIX NATURE would point out, (1) that knowing is on the way to truth, and the knowing creatures, that face the facts, survive; and (2) that truth-seeking expresses the natural activity of the healthy mind, and Nature is all for health. But it is also part of the deepest life of Man to enjoy what is beautiful, and one of the glories of the universe is its beauty. There is no place where this voice is not heard unless Man has obtruded noisily. ^Esthetic emotion thrills what is best and highest in us, and it also makes the pro- toplasmic stream sing as it flows. The correspondence is never disappointing; and those who ask most are best satis- fied. Part of the sensory delight that we have in beautiful sights in Nature may be due to Man's familiarity with them for so many hundreds of thousands of years ; but this will not explain the correspondence that there is between the beauty of Nature and the ever-changing requirements of what we may call the t spiritual eye '. In the contemplation of the supremely beautiful there is something of the satisfac- tion which religious feeling finds in music a language ex- pressing the inexpressible. The system to which we belong is more or less intelligible, we can make good sense of it; it is beautiful through and through ; but in what possible sense can it be said that there is in it anything corresponding to what we call good? If we patiently consider this question, two sets of facts present themselves. In the first place, Man began with strands of personality of pre-human origin, and some of these must have been very fine and others very coarse. We are apt to think oftener of the latter, for it is sometimes to our dismay and perplexity that they show themselves in the fabric of our life. But do we think enough of the other side, that there must VIS MEDICxVTRIX NATURE 639 have gone to the making of Mankind some very fine pre- human materials kin-sympathy, parental affection, the love of mates, some power of control and of endurance, some grit, and some gentleness. There are some springs of conduct in us that were flowing long before our race began, and while the water of some is bitter, that of others is sweet. The second consideration is that a study of the evolution- process discloses a multitude of cases in which the reward of success is given to types which are careful parents, de- voted mates, friendly kinsfolk. There is abundance of el- bowing and jostling, but many who have consulted Nature have turned away before she has finished speaking. We do not say that the extraordinarily laborious insect-mothers are ethical agents ; that would be a confusion of thought ; we say, however, that the objectively altruistic type suc- ceeds. Nature stamps not only the beautiful, but the other- regarding with the only approval which is hers to bestow success in surviving. And, unless they are uncommonly good hypocrites, many of Life's children behave as if they found living good. Thus Nature speaks to our moral as well as to our intel- lectual ear. Singling and sifting never cease, but Nature has certainly another counsel besides whetting teeth and sharpening claws. The limitations and difficulties which en- force struggle and competition are often effectively tran- scended by increasing parental care and sociality. Nature is continually taking advantage of her children's capacity for self-forgetfulness. In many races of animals success has been the reward of subordinating individual interests to those of the species. As a matter of fact, an extraordinarily large part of the energy of organisms is spent not on them- selves, but for others. Nature, we think, stamps not only 640 VIS MEDICATRIX NATUPLE the beautiful but the good with her approval ; and when we carefully consider the process of Natural Selection itself, do we not get from it a deep and ancient ethical message that the individual must be content to subordinate himself to the species, even to lose himself in its progressive life? There is an ethical undertone. 4. Humanist Value of the Study of Animate Evolution. Nature's music does not cease on a merry chord, but perhaps it has a healing power. There is at all events, a tonic virtue in contemplating the evolutionary process of which mankind is an outcome. It is not a small thing, forsooth, that we are part and parcel of an Order of Nature which has evolved for millions of years like a long-drawn- out drama to finer and finer issues; that the process of evolution has in the main " the unity of an onward advanc- ing melody " ; that all through the ages, apart from blind alleys, life has been slowly creeping and sometimes quickly leaping upwards; that while there have been many mys- terious losses even of branches from the great arbor vitse, the flowers have become consistently finer. There was a time when there were no backboned animals; then fishes ap- peared, then amphibians, then reptiles, then birds and mam- mals, and then, after various tentatives, mankind each age transcending its predecessor. As we look back, then, on the world-becoming, we see that finer and finer actors have appeared from epoch to epoch on the crowded stage, and the situations have become more and more intricate. A great web has been passing for in- computable ages from the loom of time hunger and love its warp and woof but the pattern has become more and more subtle, and it sometimes seems as if it were picturing a VIS MEDICATRIX NATURJE 641 story. Is there not meaning in the long-drawn-out but indubitably progressive evolution of the nervous system, in the increasing elaboration of behaviour, in the gradual eman- cipation of the psyche ? The bird is more of an agent than the worm more of a free agent; and the world has greater value to the bird than to the worm. Some simple creatures have only one answer to every question; but how complex is the life of the ant on the instinctive line of evolution, and of the dog on the intelligent line. Since the beginning of life there has been a growing appreciation and mastery of the world. Is it going to stop ? Perhaps no one has yet fully appreciated what may be called the principle of conservation in evolution. In a very literal sense, the higher animals are heirs of all the ages. Let us explain. Organisms have evolved by a trial-and- error method; they experiment organically, instinctively, and intelligently ; above all, perhaps, in the mysterious ante- natal life of the germ-cells they experiment in self-expres- sion just as water vapour does in snowflakes, but far more subtly. What are called variations and mutations in biologi- cal language are the organism's experiments in self-expres- sion, and these are the raw materials of progress. But, while the organism is ever making tentative sugges- tions and searching its environment with its tendrils, it is also remarkably conservative. It proves all things, but the other side is, that it holds fast that which is good. Great gains once made are not held lightly. Species become ex- tinct and races perish, but important organic inventions are carried on by some collateral lineage. It was probably some ribbon-worm that first manufactured haemoglobin the all- important, oxygen-capturing red pigment of the blood. Many backboneless animals of higher degree on different lines of 642 VIS MEDICATRIX NATUILE evolution have not got it, but the invention was too good to lose; and every one knows that all backboned animals from fishes onwards have red blood. Or again, the most primitive and in a way most puzzling kind of locomotion is that of the amosba flowing along, or rolling along like a microscopic t tank ' -in the pond. Is it not a most sug- gestive fact that our health from day to day, and the de- velopment of our nervous system, are absolutely dependent on this self-same amoeboid movement? Our white blood- corpuscles are amoeboid cells; the outgrowth of nerve-fibres in development is in some measure due to amoeboid move- ment. How far this evolutionary conservation of values goes, who shall say ? In any case there seems good reason for regarding evolution as essentially integrative. By this we mean that it makes for co-ordination, consistency, har- mony in the continual self-realisation of multitudinous forms of being. Ugliness, evil, inconsistency are disintegra- tive lapses that perish; beauty, goodness, truth even in little bits are integrative qualities that last. In any case, the big fact is, that men, bent on making much of their life, have behind them an organic momentum which is in part in line with what the best in us regards as best. Purpose and promise. When we consider the grandeur of the long-drawn-out Evolution process and the wonder of its masterpieces, and especially when we realise its general progressiveness and its conservation of great gains, two ideas rise in the mind- -purpose and promise. It is difficult to shut out the impression that Nature is Nature for a purpose. We do not think any longer of a ' directive power ' outside of the evolving organisms, but of a directive power which is bone of their bone and flesh of their flesh, a directive power analogous to that which VIS MEDICATRIX NATURE 643 we ourselves know when we command our course or send an arrow to its mark. What we must particularly take ac- count of is the main trend in evolution, making persistently for the dominance of mentality and the establishment even- tually of personality. Whether what we now experience be the goal or near the goal, it gives significance to the whole long journey. And if Man be the highest product of evo- lution, and if the central reality in our life is our clear pur- pose, may we not ask whether there is not also a purpose at the core of the world-process ? Von Baer, the founder of embryology, remarks that the naturalist is not precluded from asking " whether the totality of details leads him to a general and final basis of intentional design ", and our foregoing discussions have led us to the conclusion that a scientific description of Nature is not inconsistent with a philosophical or religious interpretation in terms of purpose which manifests itself in the order of Nature, in keeping Nature in lasting remembrance. We must, however, recog- nise that just as Man's conceived purpose transcends the mammal's perceived purpose, as that in turn transcends the lower animal's ingrained or organised purposiveness, so, but much more, will the Divine Purpose transcend our highest thoughts of it. But we deem that if we err in using the word Purpose the biggest word we have we err less griev- ously than if we used no word at all. Promise. For millions and millions of years there was throughout Nature no voice of life at all nothing to break the silence but the thunder and the cataract, the waves on the shore, and the wind among the trees. The morning stars sang together and the little hills clapped their hands, but there was no voice of life at all. The long lasting silence was first broken by insects, but they never got beyond in- 644 VIS MEDICATRIX NATURE strumental music. It is to the progressive Amphibians of the Carboniferous Age that we must look back with special gratefulness, for they were the first to get vocal cords, and, interestingly enough, a movable tongue. With them Animate Nature found a voice. In a much deeper sense, however, we may say that for millions and millions of years Nature was speechless never more than groaning and whispering, as it were. It was in Man that Nature became definitely articulate ; that the in- herent rationality was echoed. In poem and painting Man expresses his aesthetic appreciation and partial understand- ing of the system of which he forms a part; in his science he turns darkness into light; in the application of science he conquers and controls the world. Every one recognises as a big fact of animate evolution the growing differentiation and integration (i.e.., organisation) of living creatures, but another side to it is the progressive external registration. There has been woven a web of life whose pattern has become more and more intricate, as for instance in the inter-relations between flowers and flower-visiting insects. This complexifying of inter-relations has been of great importance in evolution, for it is in refer- ence to this external system that experiments are tested or even made, and that selection works. Thus, as it seems to us, the intensification of life has been in part secured and in part prompted by the growing complexity of the external Systema Naturae. Thus living creatures contribute to the evolution of their kind not only directly by exhibiting variations and by personally testing these, but also indirectly by making new patterns in the web of life. If this be so, there is for Man the hint the Open Secret that pro- gressive evolution depends not merely on the improvement VIS MEDICATRIX NATURAE 645 of the natural inheritance, and on the intensification of the individual life, but also on the ennoblement of the external heritage so much his own creation the treasures of liter- ature and art, the beautified region and city, the tradition of high ideals, and the multitudinous linkages many in sad need of amelioration in the framework of society itself. In this mood we recall Emerson's famous passage : " So shall we come to look at the world with new eyes. Nature is not fixed . . . Spirit alters, moulds, makes it. Build, therefore, your own world. " When a faithful thinker, resolute to detach every object from personal relations, and see it in the light of thought shall, at the same time, kindle science with the fire of the holiest affections, then will God go forth anew into the creation." " As fast as you conform your life to the pure idea in your mind, that will unfold its great proportions. A cor- responding revolution in things will attend the influx of the spirit. So fast will disagreeable appearances, swine, spiders, snakes [of course these words are used metaphori- cally, not zoologically], madhouses, prisons, enemies, vanish. They are temporary and shall be no more seen. The sordor and filths of nature, the sun shall dry up, and the wind exhale. As when the summer comes from the south, the snow- banks melt, and the face of the earth becomes green before it, so shall the advancing spirit create its ornaments along its path, and carry with it the beauty it visits, and the song which enchants it ; it shall draw beautiful faces, warm hearts, wise discourse, and heroic acts, around its way until evil is no more seen. The Kingdom of man over nature, which cometh not with observation a dominion such as now is beyond his dream of God- -he shall enter without more 646 VIS MEDICATRIX NATURAE wonder than the blind man feels who is gradually restored to perfect sight." Putting what we have said in a different way, we may speak of the three voices of Nature, meaning the impulses that come from the threefold- -practical, emotional, and intel- lectual relation between Man and Nature. These are the wordless voices referred to in the XlXth Psalm: " Day unto day is welling forth speech, and night unto night is breathing out knowledge ; there is no speech, and there are no words ; their voice has no audible sound ; yet it resonates over all the earth." The three voices are: Endeavour, Enjoy, Enquire. The first voice is Endeavour. What would our hereditary character be without Nature's millennial sifting of the in- surgent, the adventurous, the controlled, the far-sighted, the strenuous ? And the discipline is still binding. There is no doubt as to Nature's condemnation of the unlit lamp and the ungirt loin. One of the obvious lessons of evolu- tion is the danger of having things made too easy ! The second voice is Enjoy. As we come to know Nature, we find that everything is wonderful. " You of any well that springs may unfold the heaven of things." " It is enough if through Thy grace I've found naught common on Thy Earth. Take not that vision from my ken." As we begin to feel more at home our wonder grows into what may almost be called affection. This is true of those who have what Meredith called " love exceeding a simple love of the things that glide in grasses and rubble of woody wreck ". Science never destroys wonder or delight, but only shifts it higher or deeper. As Coleridge said, " All knowledge begins and ends with wonder, but the first wonder is the child of ignor- ance, while the second is the parent of adoration." We need to listen to this second voice which says Wonder, Enjoy, VIS MEDICATRIX NATURAE 647 Revere. It was one whose life was far from being all roses who said: To make this Earth our hermitage, A cheerful and a changeful page God's bright and intricate device Of days and seasons doth suffice. The third voice is Enquire : From the first Nature has been setting Man problems, leading him gradually on from the practical to the more abstract. Lafcadio Hearn tells us that in the house of any old Japanese family, the guest is likely to be shown some of the heirlooms. " A pretty little box, perhaps, will be set before you. Opening it you will see only a beautiful silk bag, closed with a silk running-cord decked with tiny tassels You open the bag and see within it another bag of a different quality of silk, but very fine. Open that, and lo ! a third, which contains a fourth, which contains a fifth, which contains a sixth, which contains a seventh bag, which contains the strongest, rough- est, hardest vessel of Chinese clay that you ever beheld; yet it is not only curious but precious; it may be more than a thousand years old." Indeed it is more than clay, there is an idea in it. Natural Science has to do with a similar process of un- wrapping it opens the beautiful box, it removes one silken envelope after another, trying at the same time to unravel the pattern and count the threads and what is finally revealed is something very old and wonderful the stuff out of which worlds have been spun " a handful of dust which God enchants ". For we must see the scientific Com- mon Denominator in the light of the philosophic Greatest Common Measure. Varying the metaphor, one of the foremost investigators, 648 VIS MEDICATRIX NATURAE Sir J. J. Thomson, writes : " As we conquer peak after peak we see in front of us regions full of interest and beauty, but we do not see our goal, we do not see the horizon ; in the distance tower still higher peaks, which will yield to those who ascend them still wider prospects, and deepen the feel- ing, the truth of which is emphasised by every advance in science, that ' Great are the Works of the Lord/ These are the three voices of Nature. She joins hands with us; and says Struggle, Endeavour. She comes close to us, we hear her heart beating; she says Wonder, Enjoy , Revere. She whispers secrets to us, we cannot always catch her words; she says Search, Enquire. These three voices appeal to Hand and Heart and Head, to the trinity of our being. In listening to them we may be disciplined to hear even more august voices. Man's struggles for food and foot- hold have often helped him to much higher reaches of en- deavour; to be thrilled with beauty may be a step to loving goodness ; to try to find out scientifically what is true in Nature may be the beginning of waiting patiently upon the Lord. But our point is that to listen to the three voices of Nature is in itself worth while. It is a necessary and natural discipline of the developing human spirit. We are familiar with the story of a rugged and very hu- man Hebrew prophet, who after severe discipline climbed a mountain and heard the three voices of Nature. First, there was a great and strong wind, a symbol of the practical voice, surely, which commands man to build his house upon a rock and to struggle against the storm, which teaches the sailor to trim his sails and the husbandman to prepare for the rain. Second, there was an earthquake, a symbol of the emotional voice, surely, for is there anything so awful that stirs man and beast more deeply, that moves us down VIS MEDICATRIX NATURJE 649 to the primeval bed-rock of human nature laid down in the time of the cave-dwellers. Third, there was the fire, a symbol of the scientific voice, surely, for the fire of science burns up rubbish, melts out the gold, reduces things to a common denominator, and gives light to Man. Now it seemed to the prophet that God was not in the wind, nor in the earthquake, nor in the fire, and it seems strictly correct to say that listening to the three voices of Nature is not in itself religious. But it is a good thing to listen, and it may form a preparation for religion. It was so in the prophet's case, for after the echoes of the wind and the earthquake and the fire had died away, he heard a still, small voice God's voice a sound of gentle stillness, the Margin says which spoke very incisively to him. It was a great experience to the prophet to have heard the three voices of Nature, but it meant more for him practically to hear the still small voice. And it may be that in obeying it he understood afterwards that God was in the other voices too. So when we pass from the cold evening-light of science, which the schoolmen called cognitio vespertina, to the morn- ing-light of religion, which they called cognitio matutina, we may be able to agree with Ruskin's fine words (engraved on the memorial at Keswick) : " The Spirit of God is around you in the air that you breathe, His glory in the light that you see, and in the fruitfulness of the earth and the joy of its creatures He has written for you day by day His revela- tion, and He has granted you day by day your daily bread." 5. Scientific Description of Animate Nature not Incon- sistent with Religious Interpretation. We cannot reach any religious truth or conviction along scientific lines, but we have tried to show that a careful 650 VIS MEDICATRIX NATURJE scientific description of Animate Nature is not inconsistent with a spiritual i.e., religious or philosophical interpreta- tion. Although some will not agree, we hold it to be historically true that just as there is a science that knows Nature, so there is a Religion that knows God ; and throughout our studies we have not concealed our conviction that it is unprofitable to pit against one another these two distinct ways of working towards truth. For they are not antithetic but complemen- tary. Perhaps it would be well if the devotees of Science were more aware of its limitations, perhaps it would be well if the religious who have the vision of God knew a little more about His works, but what must be sought after by both is a position from which haply there may be seen the unity of Huxley's science and Wordsworth's vision. The results of Science must, we think, be taken up as " harmonious ele- ments in a system of truth wider than themselves ; a system in whose wider light their ultimate significance for life and for the meaning of life would become manifest ? (Blewett, 1907, p. 52). We venture to hope that our study of Animate Nature may have shown it to be less daemonic and more divine than many, from Aristotle onwards, have supposed; we should regret having spoken at all if our study has led any one to suppose that Animate Nature is not greater than our greatest thought of it. For the facts of the case from first to last are so wonderful that we venture to say that no general impression of Nature reached along scientific or any other lines can be even in the direction of being true that does not sound the note of joyous appreciation and of rever- ent wonder. As Walt Whitman said, " Prais'd be the VIS MEDICATRIX NATURE 651 fathomless Universe, for life and joy, and for objects and knowledge curious." Or take part of William Watson's poem: " Nay, what is Nature's Self, but an endless Strife towards music, Euphony, rhyme? Trees in their blooming, Tides in their flowing, Stars in their circling, Tremble with song. God on His throne is Eldest of poets; Unto His measures Moveth the whole." But even that is not warm enough. We have missed the substance if the study of Animate Nature leaves us cold. Take rather this from Ralph Hodgson's Song of Honour: " I heard the universal choir, The Sons of Light, exalt their Sire With universal song; Earth's lowliest and loudest notes, Her million times ten million throats, Exalt him loud and long, And lips and lungs and tongues of grace, From every part and every place, Within the shining of his face, The universal throng." Let us listen to Goethe, at once scientific investigator and poet: " Nature! We are surrounded and embraced by her: powerless to separate ourselves from her . . . 652 VIS MEDICATRIX NATURAE We live in her midst and know her not. She is inces- santly speaking to us, yet betrays not her secret . . . She rejoices in illusion. Whoso destroys it in himself and others, him she punishes with the sternest tyranny. Whoso follows her in faith, him she takes as a child to her bosom. She wraps man in darkness, and makes him for ever long for light. She creates him dependent upon the earth, dull and heavy ; and yet is always shaking him until he attempts to soar above it ... I praise her and all her works. She has brought me here and will also lead me away. I trust her. She may scold me, but she will not hate her work. Every one sees her in his own fashion. She hides under a thousand names and phrases, and is always the same. I praise her and all her works. She is silent and wise. I trust her." But we cannot worship Nature. We cannot be grateful to a system. We cannot find abiding human satisfaction in Nature's voices alone. Invigorating, inspiring, and instruc- tive they certainly are, but they are full of perplexities, and it is with a sad wistfulness that we hear their echoes dying away in the quietness of our minds like the calls of curlews on the moor as they pass further into the mist. Happy, then, are those who have what Sir Thomas Browne called " a glimpse of incomprehensibles, and thoughts of things that thoughts but tenderly touch ". Shall we not seek to worship Him whom Nature increasingly reveals, from whom all comes and by whom all lives ? BIBLIOGRAPHY [REFERENCES TO LITERATURE Adami, J. G. Medical Contributions to the Study of Evolution. London, 1918, pp, 372, 7 pis., 20 figs. A. E. The Candle of Vision. London, 1918. Agar, W. E. Transmission of environmental effects from parent to offspring in Simocephalus vetulus. Philosophical Transactions, Royal Society of London, Series B, vol 203, 1913, pp. 319-350. Allen, Grant. Physiological Esthetics. Alexander, F. Matthias. 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[An admirable introduction, intelligible to all, and entirely reliable.] Driesch, Hans. Der Vitalismus als Geschichte und als Lehre. Leip- zig, 1905, pp. 246. Driesch, Hans. The Science and Philosophy of the Organism. 2 vols. Gifford Lectures, Aberdeen. London, 1908, pp 329 and 381. Driesch, Hans. Ueber cinige neuere " Widerlegungen '' des Vitalis- mus. Archiv Entwicklungsmcchanik, 1908, XXV, pp. 407-422. BIBLIOGRAPHY 659 Driesch, Hans. The Problem of Individuality. London, 1914, pp 84. Drummond, Henry. The Ascent of Man. The Lowell Lectures. London, 1904, pp. 444. Dugdale, Robert L. The Jukes. A study in crime, pauperism, dis- ease, and heredity. London and New York, 1910 (1st ed., 1877), pp. 120. Ellis, Havelock. The Task of Social Hygiene. London, 1912, pp. 414. Ellis, Havelock. Essays in War-Time London, 1916, pp. 252 Ellis, Havelock. The Origin of War. The Nation, January 18, 1919. Enriques, Federigo. Problems of Science. Trans by Katharine Royce. 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Jena, 1910, pp. 1-112, 2 pis, 16 figs [An excellent historical sketch, anti-vitalist, anti-Lamarckian, emphasising biological rather than psychological concepts.] INDEX Abiogenesis, 384 Abundance of life, 53 Activity, organismal, 195 Adami, Prof. J. G , 493 Adaptations in animate nature, 319 structural, 320 intra-organismal, 321 origin of, 325 evolution of, 470 Adaptiveness, 60 and purposiveness, 319, 347 Adjustments, functional, 321 Adrenalin, 398 emotion and, 622 A E , 33 /Eschylus, 1, 3 .-Esthetic delight, factors in, 267 emotion, general characters of, 260 emotion, bodily resonance and, 268 emotion, evolution of, 279 Agassiz, Louis, 488 Aliotta, 242, 637 Altruistic and egoistic activities, 314 Alevolar epithelium, 118 Ammophila, instincts of, 202 Amoeba, behaviour of, 97 reactions of, 180, 181 "mind" 1 of, 182 and mind, 517 Amphimixis, 417, 429 Amphioxus, development of, 151 Anabolism and Metabolism, 84, 86 Analytical explanation, 115 Anaphylaxis, 85 Ancestral experiments, entailed re- sults of, Anaesthetic, 248 Animal behaviour, 122, 175 diverse views on, 177 summary, 222 purposiveness in, 335 Animal, the first, 388 Animal Mind, The, 215 Animate evolution, humanist value of study of, 640 nature, correspondence of to ideals of True, Beautiful and Good, 634 Animism, early, 27 soul theory on, 240, 241 Animists, 102 Antholoba reticulata, 196 Anthony, Dr. R , 558 Anthropocentric theory, 6 Anthropoids and man, 568 " Anti-bodies " (in tapeworms) , 581 Anti-locust league, 618 Anti-toxins, 493 D'Annunzio, 101 Apartness of life, 130 of living creatures, 110 Aphid pellucida, 593 Arboreal man, 559 Archegseus, 431 Architecture, types of invertebrate, 394 Arcs, reflex, 187 Aristotle, 10, 247, 398, 449, 597 Aristotelean dictum, 169 Arrhenius formula, -114 Arthropods, nervous system of, 198 Artificers, animal, 285 Assheton, Prof. R., 150, 151, 152 Astronomy, 108 gravitational, 109 Atoms, 65 Attraction and repulsion, 151 Atwater (experiment), 112 " Automatic" regulation, 215 Automatic sifting, 327 Automatisation, 194 Autonomy of biology, 35 of psychology, 36 Awareness of meaning, 237 Bacon, Historia Naturalis, 12 Backboned animals, rise of, 394 v. Baer, K. E., 429, 488, 526 Bain, 249 Baldwin, Prof. Mark, 483 675 676 INDEX Balfour, Mr. A. J., 264, 279, 469, 565, 637 Batoson, Prof., 92, 95, 145, 363, 364, 365, 373, 411, 413, 416, 420 Bayliss, Prof., 12 Beauty, the fact of, 259 summary, 283 aspects of, 271 pervasiveness of, 62, 259 for ashes, 216 and love, 281 Beavers, 211 Becquerel, 89 Bees, homing of, 123 Behaviour, 101 what is it?, 175 effective, 97, 104 instinctive, 197 implicit, 216 and tropisms, 194 increased masterfulness of, 400 evolution of, 507, 510 Bellerophon, 387 Bergson, Prof., 21, 32, 38, 99, 169, 207, 208, 209, 234 Bernhardi, v., 241, 308, 359, 481 Bethe, 178 Big brain type, 197 Biochemistry, 160 Biococci, primitive, 15 Biogenesis, fundamental law of, 488 Biology, autonomy of, 36, 133 categories of, 165 Biological position, 166 Biological questions, two funda- mental, 353 Biological side of body and mind problem, 230, 231 * Biometer, Tashiro's, 422 Biophysics, 160 Biosphere, 354 Birds and man, 239 Birthrate, high as cause of war, 311 Blake, 269 Blewett, Prof. J. G., 372, 375, 650 Bodies, the making of, 390 Body and mind, problem of, 227 summary, 254 "Body," 229 Body-mind, 228 Body and Mind (MacDougall ), 242 Bone, appearance of, 395 Bone, structure of, 60 Bosanquet, Prof., 260, 261, 262, 269, 277 Botys hyalinalis, development of oggs of, 126 Bower birds, 263 Boyle's Law, 155 Brachet, 232 Brachydactylism, 487 Brain and behaviour, 233 Brain-life, thought-life and, 236 Brain in man, 553 Breath of Life, The, 399, 587 British Warblers, 459 Browne, Sir Thomas, 607, 652 Brownian movements, 176 Buffon, 590 Bumpus, Prof., 444, 447 Burbank, Luther, 441 Burger, 196 Burroughs, John, 587 Butler, Bishop, 401 Butler, Samuel, 72, 249, 361, 412, 441, 525 Cabanis, 236 Cairns, Prof. D. S., Candle of Vision, 33 Candle, processes involved in see- ing a, 229 Cannon, 622 Carr, Prof. Wildon, 23, 208 Carlson, 622 Castle, 412 "Categories," 110 Categories, psychological, 254 physical and chemical inade- quate to explain life, 137 Cauchy, 148 Celandine, variation in greater, 409 Cell-cycle, 388 Cell-division, 24, 92-95, 150 Cellular organisation, types of, 388 Cephalisation, 393 Ceptors, 521 Cerebral cortex, 232 in man, 553 Cesnola, 443 Cetaceans, hind limb in, 368 Chaldeans, 3 Chambers, Robert, 556 Changes not lost, 99 Change, persistence in spite of, 86 " Chain-reflexes," 190, 222 Charcot, 524 INDEX 677 Chemical specificity of milk, 81 of blood, 84 Chemical and physical laws apply to organisms, 110 Chick, development of, 20, 127 artificially reared, 198 Chickens, elimination among, 445 Child, Prof. C. M., 391, 422, 423, 610 Chinese primrose, variation in, 610 Chlamydozoa, 14 Chromosmes in man, 419 as vehicles of heritable qualities, 416 Circulation of matter, 66 Clifford, W. K., 10, 99, 246 " Cockpit " view of Nature, 290 Cognitive and conative factors in instinct, Colaptes meoeicanus, storing in- stinct in, 210 Coleridge, 28, 646 Collie-dog, intelligence in, 211 Colloids, 162 Comte, 15 Consciousness, 237 Conservation of energy, 155 and animism, 244, 245, 246 Conservation of values, 242 Consumption, criticism of, 614 Continuity, 355 of behaviour of lower and higher organisms, 211 of evolution, 373 of germ-plasm, Contractility, 176 Contrasts between realm of orga- nisms and domain of inor- ganic, 71 Control of life, 603 Control of nature, 39 Convolutas, 194 Copernicus, 5, 22 Correlation of organs, 320 of parts, 129 theory, 247 Cosmic shadows, 616 Cosmology, 6 Cosmosphere, 354 Courtship of Animals, 461, 465 Crab and anemone, 322 Crab-apple, 360 Crampton, Prof., 444 Crayfish, 82 Creationists and evolutionists, 5 Creative Evolution, 21, 234 Cresson, Prof., 306, 307 Crile, Prof., 521, 522, 622 Criteria of livingness, 79 (summary), 102 Criticism of consumption, 614 Criticism and Beauty, 264 Croce, Signor, 277 Crooke's vacuum, 16 Cruelty of Nature, 585 Crystal, 71 Crystallisation, 386 Cultivated plants, 262 Cunningham, J. T., 425, 461 Cytolysis, 93 Cytolaxis, 151 Cytotropism, 151 Dahl, 514 Dannewig, 113 Dantec, le, 525, 621 Darbishire, 511 Darwin, 13, 26, 51, 57, 235, 292, 298, 299, 300, 308, 325, 407, 411, 412, 451, 456 Erasmus, 291 Sir Francis, 374 More Letters, 594 Darwinism, 300 careless, 304 logical objections to, 490 recoil from, 492 Darwinism, 371, 460, 529 Darwinism and Human Life, 309, 445 Dastre, Prof., 386 Davenport, Prof. C. R , 445 Dearborn, Prof., 622, 623 Death, old age and natural, 591 senescence and, 589 Deathrate, selective, 444 Deep-sea fauna, 295 Definitions, 478 Democritus, 169 Dendy, Prof. A., 425 Descartes, 178, 361, 525, 637 Descent of Man, 301, 457, 458, 462, 561 Descriptive formulation the end of science, 8 Design, argument from, 325, 468, 471 Design in Nature, 469, 471 Determinist and free-will interpre- tations, 222 Development, 103 678 INDEX Development, difficulty of apply- ing mechanistic formulae to, 126 Developmental mechanics, 130 Diatoms, numbers of, 44 Dichotomoics false, 147 Differentiation and integration as standards of progress, 445 progressive, 392 in development, 128 Dipper or water-vuzel, 529 Discontinuity, 104, 167 Disease, 576 in "wild" nature, 577, 605 in controllability of, 605 Discourses on metabolism, 65 Disharmonies and other shadows, 573 (summary), 599 Disparateness of mind and body, 246 Diversions of a Naturalist, 27 Divine thought, Nature as expres- sion of, 574 Dobell, Prof. Clifford, 421 Dolbear, Prof A. E , 36 Domesticated animals, 262, 264 Domestication and cultivation, 607 Driesch, Prof. Hans, 128, 120, 130, 152, 153, 154, 171, 200, 441 Drinkwater, H , 424 Drummond, Henry, 301 Dryewina, Miss, 212 Dudley, Prof. W. M., 5, 6 Duration of life, 593 Dwarfs, 408 Dyer, Sir W. Thistleton, 385 Dysteleologies, 576 Eagle and tortoise, 211 Earland, Mr. A., 185 Earth, stages of development of, 72 Earthworm, behaviour of, 189 Ecclesiastes, 589 Educability, 556 Eel, migration of, 160 Effectitve response, life as, 165 Egg-eating snake, 323 Egg-cell, fertilisation of, 307 Egg-tooth, 61, 323 Egoistic and altruistic activities, 314 Elbinghaus, 247 Electrical theory of matter, 12 Electricity and matter, 22 Elementary functions, 80 Elements, 60 compared with species, 66 Elimination, instances of dis- criminate, 445 Ellis, Dr. Havelock, 311, 312 Embryological evidences of evolu- tion, 369 Embryos, 489 Emerson, 28, 550, 552, 646 Emotion, motion and, 624 Empirical knowledge, 38, 39 Endeavour after well-being, 57 Endomixis, 421 Energy, 163 Enriques, Prof., 70, 115, 166 Entelechy, 144, 146, 153, 154, 157, 158, 159, 160, 171, 243 Environment and Efficiency, 611 Environment, choice of, 528 transforming power of, 604 Ephemerides, brief adult life of, 426 Epicureanism, 373 Epigenesis, 366, 367 Epiphenomenalism, 227, 236 Epiphenomenalist theory, 236 Erdman, Miss, 421 Esquisse d' une philosophie de la nature, 519 Ether, 69, 70 Eugenics, 619 Eutopias, 619 Evening primrose, 413 Evolution, 366 Evolution, 463 L'Evolution cratrice, 208 Evolution and Adaptation, 460 Evolution, concept of, 353 (summary), 397 and development, 132 difficultites in regard to, 370 directive factors in, 439 fourfold, 400 human and animal contrasted, 559 lessons of, 603 of organic and human societies originative factors in, 407 Evolution of Mind, 538 Evolutionists, creationists and, 5 Evolutionist outlook, 470 Excised fragments, continued life of, 96 Experience, 101 registration of, 97 INDEX 679 Experimentation, non-intelligent, 193 Experiments in self-expression, 101 Explanation, 19, 36 analytic and synthetic, 115 Extinction of highly specialised types, 575 Eye, 114 vertebrate, 320 Fabre, 201 Fatigue, 617 Fechner, 247, 249 Feeling, function of, in our view of Nature, 25, 26 for Nature, to conserve, 30 Fitness, 60, 454 Fitnesses, 329 Flowering plants, Darwin and, 51 Flowers and insects, 467 Fluctuations, 410 Foraminifera, 278 sheilbuilding among, 185 " Forbidden degrees," 614 " Forced movements," 17, 193 " Forces of Nature," 4 Foster, Sir Michael, 81, 95 Fruit-flies, abnormality in, 610 Fugue, 361 Function and environment, changes of, 97 transforming power of, 604 Functions of the body, 117 everyday, of animal organism Fur Danoin, 488 Galeotti, 115 Galileo, 4, 5, 8 Galton, 411, 413, 479, 480, 485 Gammarus, tropism in, 193 Ganglionless animals, 196 Caol fever, 625 Gates, Dr R. R., 414, 430 Gauss, 148 Geddes, Prof. Patrick, 289, 302, 388 and Thomson, 566 General instinctive tendencies, 203 Genes, 424 Genetic method, 20 Geocentric theory, 5 Germ-cell a condensed individu- ality, 326 Germ-cells as organisms, 98, 428 Germinal origin of improvements in behaviour, 518 Gills and gill-clefts, 490 Glacier insects, 53 God or Natural Selection, 37 Goethe, 26, 29, 52, 57, 261, 306, 594, 651 Golding, Louis, 587 Goltz, 458 Good, the True and the, 283, 285 Goose, story of wounded, 239 Grammar of Science, 459 Graptolites, 575 Gravitational Astronomy, 22 Gravitation, Law of, 19, 155 Gravity, 9 Grebe, great crested, 464, 465 Gregarines, Groos, K , 459, 461, 464, 621 Ground- wasp, 198 Grouse-disease, 577 Growth, 103 Growth and Form, 112, 449 Growth, reproduction and develop- ment, 91 Grundziige der Physiologic, 181 Gudernatsch, 609 Gulls, flight of, 270 Haldane, Dr. J S, 117, 119, 120, 121, 125, 157 Hamerton, Mr., 533 Hannaq, Cannon, 270 Harmony and discord, 62 Hart, Dr Bernard, 524 Hartog, Prof M, 149, 150, 483 Harvey on development of chicks, 127 Healing power of Nature, 537 psychological aspect of, 633 Hegel, 261 Helium, 357, 477 Henderson, Prof. L. J., 73, 331 Henri, Madame, 414 Herbst, 151 Heredity, 482 Heredity, 477, 501 and personality, 498 the first determinant of life, 606 definition of, 478 rule of, 480 a condition of evolution, 480 other side of, 495 Heritage, external, 494 social, 562 Hermit crabs behaviour of, 212 Heron-Allen, E. A., 185 Hertz, 148 680 INDEX Heterogeneity in domain of inor- " ganic, 61 Hewlett, 555 Hickson, S. J., 428 Hippopotamus, 267 Historical method, 20 History, 356 Hives-bees (homing), 198 Hobbes, 36, 236 Hobhouse, Prof., 62, 215, 512, 530, 554, 595, 627 Hodgson, Ralph, 651 Hoge, Miss, 610 Holmes, S J., 458, 465 Homologies, 368 Howard, H. Eliot, 459 Hudson, 238 Human behaviour, purposefulness in, 331 Human Body, The, 557 Human life, apartness of, 305 society, 252 Humanist side of body and mind problem, 234, 235 Hume, 132, 178, 539 Humphrey, Prof , 590 " Hunger and Love," 290, 292 "Hunting" in unicellulars, 180, 185 Huxley, 19, 82, 84, 93, 95, 289, 293, 384, 548, 558, 565 Huxley's epiphenomenalism, 236 Huxley, Julian S, 54, 464 Hydra, 592 Hylopsychism, 252, 253 Ichthyosanrus, 575 Idealism, subjective, 239 " Ideal systems," 19 Identity theory, 240, 247 Imperfect adaptations, 575 Implicit behaviour, 215 Inbreeding, 560 Incommersurables, 41 Individual and the race, 477 subordination of, to species, 306 Individuality, 85, 101 of dog, 221 absence of in inorganic, 72 of species, 52 Individualities, living creatures as, 319 multitude of, 51 Indeterminism, experimental, 220 Infusorians, 183 complexity of, 54 Ingrained hereditary capacities, 218 Inheritance, natural, 494 " Inorganic," 49 Inorganic aspect of living crea- tures, 110 suitability of, for basis of or- ganic, 73 domain of the, 49-75, 335 genesis of, 356 Insignia of organisms, 97 Instinctive behaviour, 197, 514 general characters of, 200 grades of, 204 Instinct and Experience, 203 Instinct, theories of, 203 Instinct and intelligence, 206, 207, 208, 522 Insurgence of life, 53, 55 Integration and differentiation, 392 Integrative Action of the Nervous System, 238 Intelligence and instinct, 205 Intelligent behaviour in animals, 211 Interaction, 242 Interactions, between organic and inorganic, 399 Interdependence of mind and body, 233 Interpretation of Nature, 387 Interpretation of Nature, towards a philosophical, 34 Inter-relatcdness in realm of or- ganisms, 66 Inter-relations, 399 Intuition, 32 Irreducibility, 138 Irritability, 176 Isolation, 560 Issues of life, 289 (summary), 314 James, Prof. William, 92, 290, 688 Jennings, Prof., 97, 99, 158, 180, 181, 182, 183, 184, 190, 194, 195, 196, 219, 222, 432, 453, 499, 500, 510 Johannsen, 411, 453 Joly, Prof Wm , 96 Jones, Prof F. Wood, 558 Joussain, 377 Joy, psychology of, 621 Jungle Books, 301 INDEX 681 Kainogenetic characters, 488 Kant, 110, 135, 564 Katabolism, anabolism and, 84, 86 Keats, 28 Keibel, Prof. Franz, 323 Kelvin, Lord, 11, 148 Keith, Prof. A., 401, 541, 548, 549, 557 Kepler, 22 Kessler, 301 Kingsley, 328 Kipling, 301 KirchofT, 8, 10, 107 Krogh, 113, 114 Kropotkin, Prince, 302, 558 Kurtiis, 321 egg-clusters of, 61 Labyrinth, experiments with ani- mals, 214 Labyrinthodonts, 575 Lachelier, 636 Lamarckians, 492, 493 Land, transition to dry, 396 Lankester, Sir E. Ray, 27, 198, 328, 425, 556, 626 Lapsed intelligence, 216 Lashh-y, Dr. K. S ., 125, 337 Laws of Nature," 4, 9 Learning, 213 Lehfeldt (trans of Nernst's Theo- retical Chemistry), 168 Leibniz, 36 Lessing, 272 Leuckart, 92 Levick, Dr , 533 Life, the control of, 603 duration of, 593 Life and Finite Individuality, 117 121, 126, 135, 159 Life, issues of, 289 limitations of, 296 and mind, 102 mind and purpose, 344 two-fold business of, 291 Life Worth Living, Is, 290 Limits of Training in Animals, 538 Lingula, persistence of, 361 Linnsea truncatula, 123 Linna-us, 52, 54 Liver-fluke, 579 life history of, 123 Liver-rot in sheep, 455 Lives, a system of inter-related, 58 .1 Living organisms, essential char- acteristics of, 86 and not living, 79 Livingness, criteria of, 79 Little brain type, 178 Lodge, Sir Oliver, 64, 68, 70 Loeb, Prof. Jacques, 108, 192, 193, 194, 235, 620 Logos, 235, 637 Lost races, 377, 574, 575 Lotsy, 417 Lotze, 37, 246, 282, 377 Lovejoy, Prof. A O , 38, 164, 312, 325, 445, 469 Loves of the Plants, 292, 595, 596 Luther, 597 Lyell, 401 MacBride, Prof. E W., 483 MacDougall, Prof. W. , 205, 211, 242, 418, 525 MacGillivray, 306 MacNamara, Dr. N. C., 522 Mach, 8 Magic, early, 27 Making of mankind, 637 Maine, 311 Maitland, 163 Mai thus, 293 Mammalian stock, man's affiliation to, 235 McCabe, 538 Mclntyre, Dr. J. L , 234 Mclver, Prof. L., 561 Man, as an adaptive mechanism, 521 antiquity of, 401 apartness of, 553 ascent of, 397 kingdom of, 355 interpreter of Nature, Nature crowned in, 545, 565 Neandertal, 548 phylogeny of, 546 unique position of, 552 Man's Place in Nature, 18 Man's solidarity with primate stock, 551 Mantis, praying, 44 Manual of Psychology, 243 Marchant, James, 385 Markham, Gervase, 522 Marshall, Prof. Milnes, 488 Marsh, 575 Marsipiella spiralis, 185 Marsupials, adaptations in, 322 682 INDEX Mason-bee, limited instincts of, 200 Master activities of animal or- ganism, 176 Materialism, 236, 373 danger of, 620 Materialists, 102 Matter, 20, 21, 67, 163 Matter and Energy, 20, 68 Matter and Motion, 236 Maxwell, Clerk, 65, 66, 120 Mayflies, 296 Mechanism of Mendel ian inherit- ance, 425 Mechanistic descriptions, criticism of, 107, 122 of organs, inadequacy of, 108, 143 Mechanistic and vital istic theory, 169 Mechanism, vitalism or, 144 Meckel, 488 Memory, 194 Mendel, 54, 354, 362 Mendel's law, 10 Mendel ian or unit characters, 498 Mental factors in nervous disor- ders, 524 Mental processes and brain proc- esses, interdependence of, 248 Meredith, 277, 282, 455, 646 Mermaid's purse,60 Merogony, 127 Mery, 25, 28 Metabolism, mind and, 243 persistence of complex, 81 of protcids, 83 Metakinetie aspect, 153 Metchnikoff, 589 Methodological vitalism, 159 Michelson-Morley experiment, 23 Microscope, 15 Minchin, Prof. E. A., 387, 403 Minima sensibilia, 14 Minkiewicz. 206 Mind, 229, 230 Mind-body, 228 Mind in everyday life, 520 in evolution (summary), 541 Mind in Evolution, 512, 530 Mind, increasing dominance of in evolution, 400, 567 life and, 102 metabolism and, 243 " Miscellanies of Miracles," 221 Mitchell, Sir Arthur, 554 Mitchell, Dr. Chalmers, 279, 309, 310, 426, 557, 564, 634 Mitokinetism, 149 Modern man, 550 Modifiability, 604 Modification and variation, 100 Mole, adaptations of, 321 Molecules, 65 Mongoose and snake-poison, 60 Monism, psychical, 240 Monsters, 326, 327 Montague, W P., 253, 531 Montaigne, 178, 525 Morgan, Prof. C Lloyd, 168, 178, 199, 202, 205, 206, 228, 247, 253, 333, 386, 483, 513, 532, 534 T. H., 424, 460 Morphogenesis, facts of, 154 Moth and candle, 192 Movement as an element of beauty, 274 Movements, enrythmic, 275 Myers, Prof C. S , 207 Mysticism, 33 and logic, 377 Myxine, 580 Miiller, Fritz, 488 Multi verse, 291 Munsterburg, A., 181 Musculus complexus, 324 Mussels, fish and, 59 and minnows, 58 Mutations, 410, 411, 430 theory of, 451 man greatest of, 235 transmission of, 412 and variations, 326 Mutual aid, Kropotkin on, 302 Naturalism, 565 and agnosticism, 232 Naturalism and Agnosticism, 240, 527 Natural inheritance, 479 Natural selectionism, 300 theologv, 102, 103, 319 Natural selection, 57, 62, 325, 439, 442 (summary), 473, 573, 612 and struggle, 297 Nature crowned in man, 545 (summary), 567 flowing with purpose, 60 and nurture, 495 poetry, 29 tactics of, 289 three voices of, 646 INDEX 683 Neanderthal man, 547 Nematode worms, suspended ani- mation in, 89 Nernst, 168 Nerve-cells interrelations between, 232 Nervous system in anthropods and vertebrates, 198 establishment of, 186 progressive evolution of, 641 retarded development of, 233 Neurosis, 247 New departures, 100 Newton, 4, 9, 22, 28 New World monkeys, 546 Neitzsche, 100, 314 Noddy Tern, 534 Notochord, 491 "Nurture," definition of, 479 importance of, for the indi- vidual, 610 Nutritive chains, 58 Objectivity of beauty, 271 Observations on Sexual Selection in Spiders of the Family At- tidce, 461 Ohm's laws, 10 Old age and natural death, 590, 591 Old World monkeys, 546 Ontogeny, 378, 488, 492 Order of Nature, 331 Order, growth of scientific, 5 in inorganic, 65 physic-chemical, 133 biological, 133 social, 133 Organic evolution, difficulty of applying mechanistic formulae to, 131 defined, 360 in what sense continuous, 373 great steps in, 383 Organic inertia, 165 registration, 216 retention, 165 memory, 519 "Organism," 102 Organism as agent, 132 as a historic being, 125, 160 Organism and mechanism (sum- mary), 139 Organism transcending mechanism, 107, 159 Organismal registration of past, 163 Organisms and the inorganic, re- semblances and contrasts, 74 criteria of, 193 complexity of, 147 evolution of, 356 origin of, 383 nature of first, 387 Organisms, realm of, 355 contrasted with inorganic, 49-75 characteristic features of the, 50 Organogenesis, recapitulation in, 491 Originative factors in evolution (summary), 433 Origin of life, 14 Origin of Man, 559 Origin of Species, 273, 325, 407 Outlook on Nature, man's early, 3 Over-population, 294 Ovum of rabbit, 232 Owen, Sir Richard, 274 Osborn, Prof H F., 399, 449, 483 Orthogenesis, 449 Ostwald, 152 Paley, 200 Palingenetic characters, 488 Parallelism, psycho-physical, 249 Paramecium, 421, 511 behaviour of, 182, 183 Parasites, 260 life histories of, 580 ugliness of, 583 Parasitism, 376, 578 Parker, Prof. G. H., 451, 610 Theodore, 386 Parsimony, law of, 214 Pasteur, 604 Passenger pigeon, behaviour of, 536 Pathways to reality, 29 Pavlov, 622 Pearl, Prof. R, 191, 453, 498 Pearson, Prof. K., 308, 312, 444, 459, 460, 609 Mr Norman, 247 Peckham, Prof, and Mrs, 202, 461 Pedigrees of animals, 360 Penard, 387 Penguins, play among, 534, 535 Peppered moth, imitations of, 427 Perceptival factors in aesthetic emotion, 209 Periodic classification, 20 684 INDEX Persistence in spite of change, 86 of characters, 495 or organisms, 90 Personality, 5, 230 transcending organism, 599 Pervasive beauty of animate na- ture, significance of, 287 Pettigrew, Prof., 471 Petrovitch, Prof. Ivan, 621 Philanthus, 588 Philosophical interpretation of Nature, 34, 35 Philosophy of the As If, 261, 262 Philosophy, science and, 31 Phylogeny, 378, 488, 489, 492, (of man ) , 546 " Physical order," 50 Physiological registration of ex- perience, 182 state influencing action, 191 Pittdown skull, 548 Pithecanthropus, 547 Planaria, 19 Planarian, rejuvenescence in, 422 Planck, Prof. Max, 23 Plants, divergence of green, 389 evolution of, 390 Plasticity of animals, 55 of instinct, 205 Plastosomes, 127 Plato, 361, 614 Play, 621 of animals, 464 Play of Animals, 461 Plesiosaurs, 575 Poincare, 3 Pollen-basket of bee, 60 Poynting, Prof. J. H., 9, 245, 256 Poulton, Prof., 444 Pre-awareness, 532 Preconditions of behaviour, 176 Pressures, 16 Preyer, Prof., 196 Primate stem, 556 stock, 361 Primordial organisms, 389 Principles of Physiology, 112 Pringle Pattison, Prof. A., 17, 18, 38, 262, 367, 378 Probability, law of, 153 Procession caterpillars, 201 Productivity of animals, 53 Promise, 643-644 Prospective significance, 333 Proteids, metabolism of, 83 Proteins, 110 Protoplasm, 111 Protoplasmic inertia, 96 Protozoa, cell-division in, 93 Protozoa and natural death, 591 Prouho, 196 Psychoid, 245 Psychology, autonomy of, 36 Psychological categories, 254 Psychology experimental, 179 Psycho-physical individuality, 169 life, 247 Psychosis, 247 Psychoses and neuroses, 236 Ptarmigan and high altitudes, 60 Pterodactyls, 575 Punnett, Prof., 418, 447, 611 ' Pure lines," 453 " Pure perception," 31 Purpose, 642, 643 Purpose in the inorganic domain, 330 Purposiveness of Nature, 14 Purposiveness, adaptivenees and, and, 319-347 instinctive, 338 organic, 340 Purposefulness, perceptual, 338 Purposelikeness and adaptation, 341 Pycraft, W. P., 461, 465 Race, the individual and the, 477 Radium, 357, 477 Rankine, 10 Rat, black and brown, 298, 299 Rat, fertility of, 53 Rational conduct, 217, 515 Reactions varying in different in- dividuals, 190, 191 " Reality " of tho " atom," 1 1 The Neio Realism, 168 Realms of Ends, 617 Recapitulation doctrine, 488 Regenerative capacity, 632 Reflex action, 186, 512 responses, 188 theory of instinctive behaviour, 204 Reflexes and tropisms, 6 combination of, 187 control of, 523 , succession of tentative, 190 Registration, 189 Reichert and Brown, 485 Reighard, 448 Relation with nature, 33 INDEX 685 Relativity, principle of, 11 Religion, 40 natural, 42 science and, 39 Religious interpretation of Nature, difficulties, 573 scientific description not con- sistent with, 440 Reproduction, 103 "Republic of reflexes," 187 Resemblance between realm of organisms and domain of in- organic, 62 Rhythms, 268 Rhythmic activities, 94 Richet, Prof. Charles, 85 Ritter, Prof VV E , 4, 31, 154, 170 Rock record, 368 Romanes, 60, 212 Rook and mussel, 211 Rouband, 339 Rousseau, 554 Roux, 80, 128, 150 Rowland, Prof., 16 Royal Fern, 267, 268 Royce, 38 Rubner, 112 Ruffed grouse, 60 Ruskin, 274, 282, 649 Russell, Bertrand, 271, 377 G. S , 159, 160, 161, 431 Sacculina, 582 Sanderson, Sir J. B., 270, 283 Sage, Le, 11 Salp, heartbeat of, 126 Schelling, 37, 261, 282 Schiller, F. C., 282, 443 Science, Arms of, 8 Science and Life, 279 Science and Philosophy of the Or- ganism, 130 Science and philosophy, relation between, 37 and religion, 39 Scientific description not incon- sistent with religious inter- pretation, 649 Scientific inquiry, motives of, Scientific order, growing recogni- tion of a, 4 Schuster and Shipley, 21 Sea-anemone, 187 behaviour of, 188, 189 Sea-urchin, development of in ab- normal conditions, 15 Sea-urchin, a republic of reflexes, 187 and starfish, 196 Secondary sex characters, 456 Selection a determinant of life, 612 indiscriminate, 613 lethal, 446 mutual, 465 and progressiveness, 466 reproductive, 446 sexual, 456 social, 563 Selection theory, 472 criticism of, 451 subtlety of, 454 Self-development, 81 St-lf-disassimilation, 81 Self-expression, 101 Self-maintenance, 136 of organs not perfect, 87 Self-multiplication, 81 Self-preservation, 81 Self-preservative devices, 87 Self-regulation, 136 Self-repair, 88, 89 Selons, 587 Semon, 483 Semper, 409 Senescence and death, 589 Senescence and rejuvenescence, 391, 422, 591, 592 Senility, 590, 593 Sense-experience, 40 Sensori-motor experiments, 195 Sensory factors in aesthetic delight, 268 Sequence of activitites, 199 Sequoia trees, 56, 631 Serpent, beauty of (Ruskin), 274 Sexual Diamorphism, 392, 461 Sexual selection, 456 Sex-differences in instinctive be- haviour, 201 Sexes, divergence of, 391 "Seven Riddles of the Universe," 13 Shaw, 495 Shell-building (Foraminifera), 185 Sherrington, Prof., 238, 268, 523 Shipley, Dr. A., 21, 55 Silkworm disease, 604 Size and distance, 30, 31 Simplicity, false, 620 Simplifying, evolution as a process of analytic, 361 Slipper-animalcule, 54 686 INDEX Snail, freshwater, and liver-fluke, 123 Social animals, 359 Social heritage, 479, 497 selection, 563 Sociosphere, 354 Soddy, Prof. F., 19, 68, 69, 114, 153 Solar system, 71 Solipsism, 12, 240 Sollas, Prof., 401, 547 Sorley, Prof., W. R., 373 "Sorting demons" (Clerk Max- well), 120 " Soul," 229 Soul -theory or animism, Specialised types, extinction of, 574 Specificity of instinctive behaviour, 200 ' of metabolism, 84 Spectroscope, 15 Spencer, Herbert, 92, 301, 613 Spenser on numbers of sea-animals, 51 Spiders, 213 Spinoza, 267, 294 Spirals, 272 Spiritual influx theory, 372 " Spontaneity," 70 of animal behaviour, 220 Spontaneous division, 103 Sponge, 89 Starfish attacking sea-urchin, 196 behaviour of, 99 (Luidia), fertility of, 53 Starfishes, tentative movements in, 190 Stars, Chaldeans knowledge of, 3 Stentor, 184, 511 Stimulation, effects of repeated, 213 Stoicism, 373 Stout, Prof , 22, 38, 207, 243 Strategy behind evolution, 574 Struggle for existence, 57, 293-296, 588 forms of, 299, 300 interspecific, 297 intra-germinal, 429 misconception of, 301 Studies in Animal Behaviour, 458, 465 Study of Nature and the Vision of God, Blewett, 375 Stumpf, Prof., 250 Subjective idealism, 239 Successful expression, beauty as, 277 Sully, Prof, James, 358 Supremacy of mind, 242 Suspended animation, 89 Swallow, homing of, 122 Symbolism in beauty, 283 Symbols, thought-economising, 11 Synthetic explanation, 115 Synthesis, creative, 355 Systema Naturae, 52, 234 Systematisation in organic do- main, 66 Tashiro's " Viometer," 422 Taylor, Prof. A. E , 37, 38, 129 Mr. Dixie, 538 Technitella, 185, 279, 432 Teleological Faculty of Judgment, 110 Teleological Interpretation, 333 Temporal Variations, 425, 557 Temperature of blood, 120 Tentative reflexes, succession of, 190 Terns, homing of, 125, 198 Time, relativity of, 23 trafficking with, 180 Theism, 373 Theodicy, 30 Theology, 13, 313 Therodynamics, laws of, 114, 164 Theromorphists, 554 Theromorphism, 620 Things-in-general (Butler), 72 Things and living creatures, 49 Thompson, Prof. D'Arcy, 112, 135, 159, 449 Thomson, Geddes and, 463 Sir J. J., 10, 648 Miss M H, 611 Thorndike, Prof , 215 Thought-life and brain-life, 236 Torpedo-fish, 115 Tower, Prof, 414, 419 Transfer of energy, 96 Transformism, experimental, 60 Transilient variations, 411 Transmissibility of minute varia- tions. 412 Trees, effect of snow on, 445 Trial and error, method of, 182, 196, 217, 511 movements, 195 INDEX 687 Trilobites, 575 Trophallaxis, 339 Tropisms, 6, 17, 192, 512 and behaviour, 195 Tropism theory of animal beha- viour, 108 Tse-tse fly, 582 True, the Beautiful and the Good, The, 283, 319, 635 Trypansomes, 583 Two aspects theory, 229, 240, 247, 251 Tyndall's "Matter," 17, 118 Uexkull, von, 187 Ugliness, 266 Unconscious cerebration, 243 Unfathomed universe (summary), Waller, Prof., 90 Vital agency, force, 149 impulse, J44 principle, 144 Vitalism, descriptive or methodo- logical, 159, 163 Vitalism, History and Theory of, 441 Vitalism or mechanism, 144 objections to, 155 three grades of, 149 Voices of Nature, the three, 646 Voltaire, 597 Vortex, living being as a, 95 Vries, de, 411, 413, 450, 453 Wallace, A. R., 370, 371, 372, 379, 385, 460, 462, 528, 587 43 Unicellulars, general organismal activity among, 179 Unicellular organic reaction, 179 Uniformity of Nature, 24, 598 Unit characters, 424 Uniqueness of life, 145, (sum- mary), 170 of organisms, 167 Uranium, 357, 477 Usher, Archbishop, 547 Vaihinger, 261 Variability, 97, 99, 104 definiteness in, 420 Variation, 357 and modification, 100 Variations, discontinuous, 410, 412 Mendel ian, 453 origin of, 415 origin of heritable, 407 single individual, value of, 608 Van't HofTs Law, 113, 114 Varigny, de, 409 Velocities, 16 Venus' flower-basket, 275 Venus' fly-trap, 60 Vertebrates, origin of, 396 Venvorn, 83 Vestigial structures, 486 Vicarious functioning, 87 Visceral resonance, 268 Vision, habit of, 34 Vis medicatrix naturae, 631-652 Vital agency, is there a non-per- ceptual, 153 War among savages, 311 War, " Nature's sanction " for, 308 Ward, Prof. James, 38, 240, 244, 254, 266, 484, 527, 528, 617 Washburn, Miss, 182, 214, 215 Wasps, instinct of, 202 instinctive purposiveness in, 338 Wastefulness in Nature, 594 Watson, Prof. J. B , 125, 337, 534, 538 William, 651 Web of life, 59 Weber, Prof Max, 61 Weismann, 61, 417, 446, 480, 481, 558 Weldon, Prof , 444 Well-being, endeavour after, 304 Wheeler, 339 Whelk, egg-capsules of, 303 Whirlpool, living being as a, 82 White, Gilbert, 282 Whitman, 282, 536, 538, 539, 650 Walt, 33 Wild traits in tame animals, 486 Will, 156 as guiding power, 245 to live, 53. 56 Winwarter, 420 Wonder, 28 Wonder of Life, 122 Woodruir, Prof, 54, 421 Woodward, Dr Smith, 549 Wordsworth, 28, 32, 268, 282 Yucca flower and moth, 109, 199 Yung. Prof E, 198