SEXUAL HORMONES AND MORPHOGENESIS 461 



fully confirmed by experiments recently performed by Zawa- 

 dowsky (1922). It has long been known from certain experi- 

 ments by Morgan and Goodale (1912), that a cross of a black 

 male Langshan and a female barred Plymouth Rock gives in 

 the first generation barred cocks and plain black hens. If my 

 view is correct, castration of a black hen of the first generation 

 will cause the appearance of the male plumage of a Langshan 

 and not that of a Plymouth Rock cock. This actually happened 

 in an experiment by Zawadowsky who castrated hens of the 

 first generation. The females of the first generation inherit the 

 characters of the neutral form of the strain to which the male 

 parent belongs. Zawadowsky writes that he expected to obtain 

 by castration of cocks and hens of the first generation a form 

 common to both sexes. But his expectation was not justified. 



A passage in Darwin's book on "Variation'' may be quoted 

 here: "We can in this way understand how, for instance, it is 

 possible for a good milking cow to transmit her good qualities 

 through her male progeny to future generations, for we 

 can confidently believe that these qualities are present, though 

 latent, in the males of each generation." The mechanism of 

 such a transmission of a female character by the male is easy 

 to explain ; the male transmits a certain character of the asexual 

 soma, i.e., the capacity to react to the female sexual hormones 

 in a manner characteristic of his strain. 



Recently Pezard and Cavidroit (1922 b) have adopted the idea 

 of a neutral form influenced by sex hormones into the genetic 

 analysis of sheep of the cross Dorset x Suffolk. They have 

 shown that the interpretation of the facts here observed be- 

 comes perfectly clear if this principle is made use of. The dis- 

 tinguished French author Cuenot (1923), who gave an analysis of 

 the theory of Pezard and Caridroit from the point of view of one 

 studying heredity,has also come to the conclusion that the theory 

 is completely in accord with the known experimental results. 



If we accept the explanation given above of the transmission 

 of sex characters in mammals and birds by the opposite sex, it 

 seems necessary to assume that the sex specific hormones are 

 the same in different species. Certain experiments of Bouin 

 and Ancel on guinea pigs and of Pezard on fowls described in 

 foregoing chapters (see pp. 94, 95), show that a species specifity 

 of sexual hormones is not very probable. Zawadowsky con- 

 firmed the observations of Pezard. He brought about the 



