SEXUAL HORMONES AND MORPHOGENESIS 449 



further, both a male and a female fertilized egg give rise to an 

 asexual or identical soma, which is feminized or masculinized 

 by hormones produced by the sex gland, this might be caused 

 by the biochemical differences between male and female 

 becoming localized during embryonic development in the sex 

 gland when cellular differentiation is proceeding. We must 

 suppose that every inborn abnormahty is due to a certain 

 biochemical difference or biochemical abnormality in the 

 fertilized egg, and we must further assume that this abnormality 

 becomes later on localized in a certain group of cells, being 

 really nothing more nor less than a morphological manifestation 

 of such a localization. It suffices to mention the inherited 

 pigmentary spots, double fingers, retinitis pigmentosa, etc. In 

 all these cases the whole soma remains normal throughout life, 

 and is not influenced by the biochemical abnormality present 

 in the fertilized egg. In a similar way the soma of the embryo 

 may remain identical in both sexes till the time when the sex 

 gland, which becomes differentiated and is the morphological 

 manifestation of the biochemical difference between a male 

 and female fertilized egg, begins its hormonic action. 



We see that the biochemical difference existing between a 

 male and female fertilized egg is so far not opposed, as Kammerer 

 (1919, p. 372) thinks, to our hypothesis of the asexuality of the 

 embryonic soma, this biochemical difference becoming localized 

 and causing differentiation of a male or female sex gland, which 

 determines a male or female reaction on the part of the equi- 

 potential soma. Here, however, the question again arises 

 whether such an assumption can be brought into line with the 

 theory of the sex chromosome. 



C. FIXATION OF SEX CHARACTERS. 



That male and female somatic cells are different from the 

 beginning, and that rudimentary sex characters are already 

 present in a latent state during the earliest stages of embryonic 

 development, seem to be proved at first thought by the fact 

 that sex characters persist to a certain degree after removal 

 of the sex gland and after cross-grafting of ovaries or testes. 

 There is never complete atrophy of the uterus in the female, or 

 of the penis, the prostate and seminal vesicles in the male after 

 castration; there is rarely a transformation into a condition 

 which really could be regarded as a neutral one, as with the 



