NATURE 



21 



THURSDAY, SEPTEMBER 13, 1917. 



FOUNDATIONS OF BIO-PHYSICS. 

 On Growth and Form. By D'Arcy Wentworth 

 Thompson. Pp. xv + 793. (Cambridge : At 

 the University Press, 1917.) Price 21s. net. 



THIS book, at once substantial and stately, is to 

 the credit of British science and an achieve- 

 ment for its distinguished author to be proud of. 

 It is like one of Darwin's books, well-considered, 

 patiently wrought-out, learned, and cautious — a 

 disclosure of the scientific spirit. It is an appli- 

 cation of some of the concepts of physical science 

 and sundry mathematical methods to the study 

 of organic form. "My sole purpose is to corre- 

 late with mathematical statement and physical law 

 certain of the sijmpler outward phenomena of 

 organic growth and structure or form : while all 

 the while regarding, ex hypothesi, for the pur- 

 poses of this correlation, the fabric of the organism 

 as a material and mechanical configuration." "Of 

 how it is that the soul informs the body, physi il 

 science teaches me nothing. ... But of the con- 

 struction and growth and working of the body, 

 as of all that is of the earth earthy, physical 

 science is, in my humble opinion, our only teacher 

 and guide." We think that it will be difficult to 

 justify the word "only," for in the working of 

 the body the soul (to use the author's dualistic 

 terminology) takes part, as when a strong emotion 

 influences our suprarenals, and, willy-nilly, we are 

 back in psycho-biology. 



The author begins with the general "principle 

 of similitude " first laid down by Galileo, who 

 showed that " neither can man build a house nor 

 can Nature construct an animal beyond a certain 

 size, while retaining the same proportions and em- 

 ploying the same materials as "sufficed in the case 

 of a smaller structure." The exposition of this illus- 

 trates in a vivid way "the profound differences of 

 physical property and potentiality which are asso- 

 ciated in the scale of magnitude, with simple dif- 

 ferences in degree." This is introductory to a 

 fine discussion of the rate of growth, for the form 

 of the organism is usually a direct expression of 

 a^ rate of growth which varies according to its 

 different directions. 



"The velocities in different directions tend to 

 maintain a ratio which is more or less constant 

 for each specific organism ; and to this regularity 

 is due the fact that the form of the organism is 

 in ireneral regular and constant." 



The author has dwelt most on those aspects of 

 organic growth which have their analogies among 

 inanimate things. He says comparatively little in 

 regard to the regulative phenomena which are so 

 distinctive in the growth of organisms ; and his 

 reference to the experiments of Gudernatsch, for 

 instance, is inadequate. Not enough is allowed, 

 as it seems to us, for the extraordinary differences 

 of form which may result from a slight environ- 

 mental difference — for instance, in the experimen- 

 tally altered fates of the indifferent larvae of Bonel- 

 NO. 2498, VOL. 106] 



lia. The final form depends on the occurrence or 

 non-occurrence of certain differentiations, and that 

 depends on biochemical conditions. Then again, the 

 remarkable disturbances of form which result from 

 the introduction of toxic substances into develop- 

 ing embryos (see Werber's work) suggest that 

 form depends on more than accelerations and 

 retardations of growth in different directions. 



"The cell, which Goodsir spoke of as a ' centre 

 of force, ' is in reality a ' sphere of action ' ol 

 certain more or less localised forces ; and of these, 

 surface-tension is the particular force which is 

 especially responsible for giving to the cell its 

 outline and its morphological individuality." In 

 a fascinating discussion Prof. Thompson shows 

 that cell-division and other intra-cellular 

 phenomena may be tentatively explained as the 

 results of a conflict between surface-tension and 

 its opposing forces. He favours the provisional 

 assumption that "the phenomena of karyokinesis 

 are analogous to, if not identical with, those of 

 a bipolar electrical field." This leads on to an 

 interpretation of the forms of free cells as essen- 

 tially dependent on surface tension. "The simple 

 fact is that the agreement of cell-forms with the 

 forms which physical experiment and mathemati- 

 cal theory assign to liquids under the influence 

 of surface tension, is so frequently and often so 

 typically manifested, that we are led, or driven, 

 to accept the surface tension hypothesis as gener- 

 ally applicable and as equivalent to a universal 

 law." 



Utilising the facts of adsorption and Macallum's 

 fine researches, the author shows very cleverly 

 how apparent exceptions may prove the rule. He 

 proceeds to the more complex problem of inter- 

 preting the forms of cells in aggregates, utilising 

 Leduc's remarkable "artificial tissues," and he 

 shows the courage of his convictions in attackmg 

 the problem of the formation of blastula and gas- 

 trula. In an elaborate survey of a great variety 

 of tissues he shows that it is possible to go a 

 long way in interpretation with the help and 

 guidance which the phenomena of surface-tension, 

 thfe laws of equilibrium, and the principle of 

 minimal areas are at hand to supply. Attention 

 is directed to the fact that " all possible groupings 

 or arrangements whatsoever of eight cells (where 

 all take part in the surface of the group, none 

 being submerged or wholly enveloped by the rest) 

 are referable to some one or other of thirteen 

 types or forms," or probably fewer than thirteen, 

 "for there is reason to believe that, out of the 

 total number of possible groupings, a certain small 

 number are essentially unstable, and have at best, 

 in the concrete, but a transitory and evanescent 

 existence." 



A very interesting chapter deals with con- 

 cretions, spicules, and spicular skeletons. The 

 form of the spicule may depend simply on its 

 chemical nature ; or the inorganic solid material 

 may be laid down in conformity with the shapes 

 assumed by the cells, tissues, or organs ; or there 

 may be intermediate cases where the molecular 

 forces play their part in conjunction with, and 



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