328 



NATURE 



[September 7, 191 1 



Globigerina), or, with all intermediate degrees, may vi a J 

 nearly wholly enwrap the first. Take any specific angle 

 ■ lit act and presume the same conditions to be main- 

 tained, and therefore the same angle to be repeated, as 

 each successive chamber follows on the one before, and 

 you will thereby build up regular forms, spiral or alternate, 

 that correspond with marvellous accuracy to the actual 

 forms of the Foraminifera. And this case is all the more 

 interesting, because the allied and successive forms so 

 obtained differ only in degree in the magnitude of a single 

 physical or mathematical factor ; in other words, we get 

 not only individual phenomena, but lines of apparent 

 orthogenesis, that seem explicable by physical laws, and 

 attributable to the continuity between successive states in 

 the continuous or gradual variation of a physical condition. 

 The resemblance between allied and related forms, as Hart- 

 mann demonstrated and Giard admitted years ago, is not 

 always, however often, to be explained by common descent 

 and parentage, 1 



In the segmenting egg we have the simpler phenomenon 

 of a " laminar system," uncomplicated by the presence of 

 a solid framework ; and here, in the earliest stages of 

 segmentation, it is easy to see the correspondence of the 

 planes of division with what the laws of surface-tension 

 demand. For instance, it is not the case (though the 

 elementary books often represent it so) that when the 

 totally segmenting egg has divided into four segments, the 

 four partition walls ever remain in contact at a single 

 point ; the arrangement would be unstable, and the posi- 

 tion untenable. But the laws of surface-tension are at 

 once seen to be obeyed when we recognise the little cross- 

 furrow that separates the blastomeres, two and two, leav- 

 ing in each case three only to meet at a point in our 

 diagram, which point is in reality a section of a ridge or 

 crest. 



Very few have tried, and one or two (I know) have 

 tried and not succeeded, to trace the action and the effects 

 of surface-tension in the case of a highly complicated, 

 multi-segmented egg. But it is not surprising if the 

 difficulties which such a case presents appear to be formid- 

 able. Even the conformation of the interior of a soap- 

 froth, though absolutely conditioned by surface-tension, pre- 

 sents great difficulties, and it was only in the last years 

 of Lord Kelvin's life that he showed all previous workers 

 to have been in error regarding the form of the interior 

 cells. 



But what, for us, does all this amount to? It at least 

 suggests the possibility of so far supporting the observed 

 facts of organic form on mathematical principles as to 

 bring morphology within or very near to Kant's demand 

 that a true natural science should be justified by its rela- 

 tion to mathematics. 2 But if we were to carry these prin- 

 ciples further, and to succeed in proving them applicable 

 in detail, even to the showing that the manifold segmenta- 

 tion of the egg was but an exquisite froth, would it wholly 

 revolutionise our biological ideas? It would greatly modify 

 some of them, and some of the most cherished ideas of 

 the majority of embryologists ; but I think that the way 

 ready paved for some such modification. When Loeb 

 and others have shown us that half, or even a small por- 

 tion, of an egg, or a single one of its many blastomeres, 

 can give rise to an entire embryo, and that in some cases 

 any part of the ovum can originate any part of the 

 organism, surely our eyes are turned to the <>; 



nt in the matter of the egg (not to speak of a pre- 

 siding entelechy), and away from its original formal opera- 



of division. Sedgwick has told us for many years 

 that we look too much to the individuality of the individual 

 cell, and that the organism, at least in the embrvonir bodv, 



continuous syncytium. Hofmeister and Sachs have 

 dly told us that in the plant, the growth of the n 

 the growth of the organ, is the primary fart ; and Di i 

 has summed up the matter in his aphorism, Die r 



Zellen, nichi die Zelle bildet Pflanzen. And in many 

 other ways, as many of you are well aware, the extreme 



Cf. 1 Disco inauenrale,' Bi (3), r, 1888. 



tch behaup 



V, i.,,.,i-,ch:ifl ansetn.ti- 



anzutreffen ist."— Kant, in Preface to "Metaphys. Anfangsgriinde der 

 Naturwii (Werke, ed. Hartenstein, vol. iv. p. 360). 



M '. 21S4, VOL. 87] 



position of the cell-theory, that the cells are the ultimate 

 individuals, and that the organism is but a colony of quasi- 

 independent cells, has of late years been called in question. 



There are no problems connected with Morphology that 

 appeal so closely to my mind, or to my temperament, as 

 those that are related to mechanical considerations, to 

 mathematical laws, or to physical and chemical processes. 



I love to think of the logarithmic spiral that is engraven 

 over the grave of that great anatomist, John Goodsir (as 

 it was over that of the greatest of the Bernouillis), so 

 graven because it interprets the form of every molluscan 

 shell, of tusk and horn and claw, and many another organic 

 form besides. I like to dwell upon those lines of 

 mechanical stress and strain in a bone that give it its 

 strength where strength is required, that Hermann Meyer 

 and J. Wolff described, and on which Roux has bestowed 

 some of his most thoughtful work; or on the " stream- 

 lines " in the bodily form of fish or bird, from which the 

 naval architect and the aviator have learned so much. I 

 admire that old paper of Peter Harting's in which he 

 paved the way for investigation of the origin of spicules, 

 and of all the questions of crystallisation or pseudo-crystal- 

 lisation in presence of colloids, on which subject Lehmann 

 has written his recent and beautiful book. I sympathise 

 with the efforts of Henking, Rhumbler, Hartog, Gallardo, 

 Leduc, and others to explain on physical lines the pheno- 

 mena of nuclear division. And, as I have said to-day, I 

 believe that the forces of surface-tension, elasticity, and 

 pressure are adequate to account for a great multitude of 

 the simpler phenomena, and the permutations and com- 

 binations thereof, that are illustrated in organic Form. 



I should gladly and easily have spent all my time this 

 morning in dealing with these questions alone. But I was 

 loath to do so, lest I should seem to overrate their import- 

 ance, and to appear to you as an advocate of a purely 

 mechanical biology. 



I believe all these phenomena to have been unduly 

 neglected, and to call for more attention than they have 

 received. But I know well that though we push such 

 explanations to the uttermost, and learn much in the so 

 doing, they will not touch the heart of the great problems 

 that lie deeper than the physical plane. Over the ultimate 

 problems and causes of vitality, over what is implied in 

 the organisation of the living organism, we shall be left 

 wondering still. 



To a man of letters and the world like Addison, it came 

 as a sort of revelation that Light and Colour were not 

 objective things, but subjective, and that back of them 

 lay only motion or vibration, some simple activity. And 

 when he wrote his essay on these startling discoveries, he 

 found for it, from Ovid, a motto well worth bearing in 

 mind, causa latet, vis est notissima. We may with 

 advantage recollect it when we seek and find the Force 

 that produces a direct Effect, but stand in utter perplexity 

 before the manifold and transcendent meanings of that 

 great word " cause." 



The similarity between organic forms and those that 

 physical agencies are competent to produce still leads some 

 men, such as Stephane Leduc, to doubt or to deny that 

 there is any gulf between, and to hold that spontaneous 

 generation or the artificial creation of the living is but a 

 footstep away. Others, like Delage and many more, see 

 in the contents of the cell only a complicated chemistry, 

 and in variation only a change in the nature and arrange- 

 ment of the chemical constituents ; they either cling to a 

 belief in "heredity," or (like Delage himself) replace it 

 more or less completely by the effects of functional use 

 and by chemical stimulation from without and from 

 within. Yet others, like Felix Auerbach, still holding to 

 a physical or quasi-physical theory of life, believe that in 

 the living bodv the dissipation of energy is controlled by a 

 guiding principle, as though by Clerk Maxwell's demons; 

 thai for the living the Law of Entropy is thereby reversed : 

 and that Life itself is thai which has been evolved to counter- 

 act and battle with the dissipation of 1 net gy. Berthold, who 

 first demonstrated the obedience to physical laws in the 

 fundamental phenomena of the dividing cell or segmenting 

 egg, recognises, almost in the w-ords of John Hunter, a 

 quality in the living protoplasm, sui generis, whereby its 

 maintenance, increase, and reproduction are achieved. 

 Driesch, who began as a "mechanist," now, as we have 



