July 6, 1917] 



SCIENCE 



23 



istlcs, are also found to have assumed the type 

 of fat metabolism which characterizes the nor- 

 mal female crab. How mucli these facts con- 

 tribute to, and how completely they adjust 

 themselves to, our own general theory, will be 

 realized only after a moment's reflection. 



A glance at the diagram indicates three 

 other groups of animals which experimental 

 work has thrown into the general question of 

 the control of sex. The information at hand 

 for these forms does not so expressly concern 

 the egg as does that from the preceding cases, 

 but all of these latter groups are concerned 

 with early stages — some of them with the 

 generation preceding the egg whose sex seems 

 influenced by conditions. The results of stud- 

 ies of the first of these groups— Hydatina — are 

 of such a kind as to show that they are in gen- 

 eral accord with the metabolic diiierentials of 

 all of the previously mentioned cases of sex- 

 control. One can scarcely doubt that change 

 of food, and increased oxygen supply are con- 

 sonant with increased metabolism, just as the 

 studies of Whitney^'' particularly, and later of 

 Shull,^^ have shown that these changes lead to 

 the appearance of male-producing daughters. 



The second of these groups — the Daphnids — 

 have been studied by three independent in- 

 vestigators who agree upon two points that are 

 of importance in the question of the control of 

 sex, and to the general theory of sex as stated 

 here, though the results throw little light on 

 precisely what is causally involved. Issako- 

 witch,i° Woltereck^^ and Banta,^* all find nu- 

 merous sex-intermediates in a material for 

 which all agree that the type of reproduction — 

 sexual or asexual — is influenced by environ- 

 mental conditions. All further agree that 

 " luifavorable conditions " (or is it a change 

 from favorable conditions?) tends toward sex- 



" Science, N. S., Vol. 39, June 5, pp. 832-33, 

 1914. Also Jour. Exp. Zool., A'ol. 17, November, 

 1914, and later papers. 



15 Abstracts of Amer. Soc. Zool., December 

 meeting, Science, N. S., Vol. 43, 1916. 



M Biol. Centralbl., Vol. 25, 1905. 



1-T Intern. Bev. d. gesammt. Hydrohiol. u. Hy- 

 drogr., Vol. 4, 1911-12. 



18 Carnegie Year Book, 1915, and Froc. Nat. 

 Acad. Sci., Vol. 2, October, 1916. 



ual reproduction, while " favorable conditions " 

 favor asexual reproduction. 



In the third of these groups — the moths — 

 the studies of Goldschmidt, and Goldschmidt 

 and Poppelbaumji" and the work of Machida, 

 have demonstrated again sex-intermediates of 

 various grades. Moreover, it has been shown 

 that from among the various geographical 

 races of moths certain matings can be ar- 

 ranged which produce rather definite types of 

 male- or female-intermediates — or sex-inter- 

 grades, as Goldschmidt elects to call them. 

 And further, from pairs involving still other 

 species still other levels or grades of sex- 

 intermediates may be freely obtained. A 

 more or less factorial basis of the phenomena 

 has hitherto been used in the discussion of 

 these results; but recently Goldschmidt-" has 

 stated that " very important new facts will 

 be published later which will probably enable 

 us to replace the symbolistic Mendelian lan- 

 guage, used here, by more definite physico- 

 chemical conceptions." Such newer descrip- 

 tions — we would say — is wholly in line with 

 the requirements of present data on sex. In 

 Whitman's and our ovm material it has been 

 clear from the first that the results far over- 

 step the possibility of treating them in Men- 

 delian terms, for it has been apparent from 

 the beginning that we have had to do not 

 with three or four points merely, but with a 

 flowing graduated line. In the work with the 

 moths, however, sex is clearly described in 

 quantitative terms,. and we can readily believe 

 that when the functional basis of sex can 

 there be identified, sex will be found to accord 

 with metabolic grades there, as it does else- 

 where. 



It is clear then that all of the animal-forms 

 for which there is reasonable evidence of sex- 

 control show important correspondences with 

 the situation fully elucidated in the pigeons. 

 And that where the sex-differentials known to 



IB Goldschmidt u. Poppelbaum, Ztschr. induct. 

 Ahstammungsl., Vols. VII. (1912), and XII. 

 (1914), and other papers 1913-16 by both au- 

 thors. See R. Goldschmidt, below. 



20 E. Goldschmidt, Amer. Nat., Vol. L., Decem- 

 ber, 1916. 



