December 29, 1923] 



NA TURE 



929 



That a correlation of some sort does exist between 

 rate of developmental processes and nature of gene 

 appears to be established ; but whether there exists 

 the exact chain of events imagined by Goldschmidt 

 is a matter for further verification. 



How valuable is the conception of rate of pro- 

 duction of substances in ontogeny is seen by the rapid 

 application which it has found in other fields. Crew 

 has applied this idea to the explanation of various 

 puzzling abnormalities of the reproductive organs to be 

 found in mammals, and by so doing has removed them 

 from the lumber-room where they lay labelled with the 

 meaningless title of " pseudo-hermaphroditism " to a 

 place in a coherent biological scheme. It appears 

 more than probable that the determining factor in 

 Amphibian metamorphosis, with all its curious varia- 

 tions from species to species, is simply the relative 

 rate of thyroid growth. It will assuredly prove that 

 the same concept will be of prime importance as regards 

 the other endocrine glands in all their functions of 

 irrowth-regulation and of initiating new phases such as 

 puberty. In brief, the ideas of physical chemistry are 

 thus being introduced into embryology, and dynamic 

 ways of thinking substituted for static. 



So much for the important positive results, both of 

 fact and theory, which flow from Goldschmidt's work. 

 It remains to criticise some of his details. 



We think it right in the first place to emphasise the 

 fact that the well-known curves illustrating the physio- 

 logy of intersex production (p. 95) are quite hypo- 

 thetical in their details — a fact not sufficiently brought 

 out in the text. They could be drawn in a considerable 

 number of quite other ways and still satisfy the facts. 

 In particular, this applies to the representation of the 

 curve for production of " female " substance as rising 

 to a maximum and then sinking again. This is of 

 great theoretical importance if really true ; but no 

 adequate discussion is given of the reasons for the 

 adoption of this particular curve, nor for the rejection 

 of, e.g., a curve which continued to rise throughout life. 



The same, mutatis mutandis, is true of various other 

 of the curves presented later for other organisms — 

 although here their hypothetical nature is made clearer. 

 We think that in many cases it would have been equally 

 easy to employ the idea of alteration in susceptibility 

 of tissues to a constant stimulus (as exemplified, e.g. 

 in the alteration in susceptibility of Anuran limbs to 

 thyroid at metamorphosis) instead of that of alteration 

 in the amount of morphogenetic substance (intensity of 

 stimulus). 



We note the absence of reference to Haldane's 

 interesting work (in reality a corollary of Goldschmidt's 

 own principles) that when one sex is reduced in numbers 

 or abnormal in structure as a result of a varietal or 



NO. 2826, VOL. I 12] 



specific cross, it is — not always the male or always 

 the female, but — always the heterogametic ; and also 

 wonder why play is not made (pp. 222-224) with the 

 idea that sex-linked semi-lethal factors account for the 

 well-known differential elimination of males before and 

 soon after birth in man and other mammals — an idea 

 which at least gives full formal explanation of other- 

 wise incomprehensible facts. 



In his discussion of human sexual abnormalities 

 (p. 243) the author has only been thinking in terms of 

 his previous Lymantria scheme, which will give greater 

 or lesser sex-transformation as a result of faulty balance 

 of sex-genes : Crew's recent papers on goat and pig 

 intersexuality suggest another and simpler explana.tion, 

 in the idea of abnormally slow production of the male 

 hormone, but without any switch-over from one sex to 

 the other. No reference is made to the classical work 

 of Pezard on birds, in which the effect of the gonad 

 hormones upon growth-rate of sexual characters is so 

 ably analysed. 



These, however, are matters of comparatively minor 

 moment. The main thesis of the book stands, and is 

 of great value. In addition, various subsidiary topics 

 are discussed with great lucidity. We especially com- 

 mend the section on secondary sexual characters. The 

 treatment is not new, but so clear and incisive that 

 after reading it there should be no excuse for the not 

 uncommon misconception that the inheritance of such 

 characters throws any light upon or is in any way 

 correlated with the inheritance of sex itself, save only 

 that once sex is determined, it controls the expression 

 of one or the other set of secondary characters. 



The well-known difference between the physiology of 

 sex-determination in insects and vertebrates — in the 

 former independent of all gonadial influence, in the 

 latter put under this influence from a very early period 

 of ontogeny — the author correlates with the general 

 shortness of life in insects as against its greater length in 

 the higher group. This is an extremely suggestive idea ; 

 it will be interesting to see whether subsequent research 

 upon the connexion of gonad and sexual characters in 

 other invertebrates will bear it out. Finally, after the 

 mass of nonsense and vague theorising that has been 

 written on the sex-ratio, we commend his chapter on 

 the subject as an admirable tonic. 



It has seemed worth while to go into some detail 

 regarding the thesis and scope of the book, in spite of 

 its having been first published in German three years 

 ago, since here for the first time are English readers 

 provided with a translation (which, since Goldschmidt 

 has incorporated recent work, is also a second edition). 

 The book is intended for medical men and others, such 

 as lawyers or sociologists, who may have occasion to 

 study the problems of sex, as well as for the professional 



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