ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 443 



challenge to Kammerer to produce more satisfactory evidence than the 

 very inadequate figures on which he bases his claim to have proved 

 Mendelian segregation in regard to an acquired character. No specimen 

 having been furnished, the discussion of this important point must, says 

 Bateson, await a repetition of the experiment. Boulenger's paper con- 

 cludes with the suggestion that it was the large size of the eggs that 

 enabled the ancestors of Alijtes to take to oviposition on land, and not 

 that the character of the eggs has been modified to that effect. 



Sex and Heredity.* — R. Goldschmidt discusses some experiments 

 which throw further light on the sex problem. He refers first to three 

 outstanding facts : — 1. Cytologically, one of the sexes, the heterogametic 

 sex, contains only one X-chromosome ; the other, the homogametic sex, 

 contains two. As the maturation-division separates entire chromosomes, 

 the heterogametic sex produces two kinds of sex-cells, with and without 

 X-chromosomes. But the homogametic sex produces only one kind, all 

 with X-chromosomes. Chance fertilization produces again the two 

 parental combinations, that is, the tw^o sexes. 2. Mendelian experiments 

 show that one sex is heterozygous for the sex-factors, say Ff ; the other 

 homozygous, say FF ; the first one produces two kinds of gametes, the 

 second only one. Chance fertilization results in equal numbers of the 

 parental combinations. 3. Experiments on sex-limited inheritance have 

 shown that the two sets of facts are the same, that the X-chromosomes 

 are the vehicles for the distribution of the sex-factors. If we state, 

 further, that there are animals in which the heterozygous sex is the 

 female, and others in which it is the male, we know the elementary facts 

 from which any further study of the sex-problem has to start. 



But what are the sex-factors, and how do they determine sex ? Are 

 the two sexes clean-cut alternatives, or are they nothing but limiting 

 points of a series, which might approach each other or even become 

 interchanged ? One line of approach to an answer is to be found in 

 the study of the influence of the internal secretion of the sex-glands in 

 castration and transplantation experiments. Another line is to be found 

 in the study of sexual abnormalities in insects. Goldschmidt has worked 

 with the gipsy-moth. 



Crosses of Japanese females with European males yield normal 

 oflf-spring ; the reciprocal cross yields normal males and females with 

 admixtures of male characters. This gyuandromorphism is called by the 

 author intersexuahty. It segregates, Fo giving normal forms and inter- 

 sexual forms. In some experiments the hybrid females are normal, the 

 males become intersexual. 



The explanation offered is the following : — Both sexes contain the 

 primordia for either sex. In both sexes, irrespective of the constitution, 

 both primordia might become patent. Which one is to appear depends 

 entirely upon the quantitative relation of both. The female factorial set 

 and the male factorial set act independently and with a definite quantita- 

 tive strength, which may be called their potency or valency. It might 

 mean a certain concentration of enzyme ; when the preponderance of one 



* Amer. Nat., 1. (1916) pp. 705-18. 



