SEXUAL HORMONES AND MORPHOGENESIS 475 



that here we have an hormonic effect which is a non-sex-speciiic 

 one, hke that on the hypophysis. But the condition is reaUy 

 somewhat different. Though there are differences between 

 the male and female hypophysis in weight and histological 

 structure, it seems that they are induced only by pregnancy. 

 On the other hand, the length of the long bones is a very 

 pronounced sex character; whenever measurements have been 

 made the differences between male and female were found to be 

 very marked, both for the upper and lower extremities (see the 

 data in Martin, 1914, pp. 983, 992, 1016, 1017, 1040). One 

 must suppose that male and female sexual hormones influence 

 the growth of the bones in a quantitatively different way; 

 possibly the quantity of the respective hormones entering 

 the circulation and the rhythm of their secretion are different 

 in male and female. Owing to this there is brought about a 

 quantitatively different condition which is a sex specific effect. 

 But the dependence of morphogenetic processes and that 

 of the metabolism upon sex hormones is in reality much more 

 compHcated than can be indicated under the expressions sex- 

 specific or non-sex-speciiic activity. First of all, it must never 

 be forgotten that the other organs producing internal secretions, 

 which have such an enormous influence on all the processes 

 going on in the organism, especially during growth, are also in- 

 fluenced by the internal secretions of the sex gland. It would 

 be very difficult to say how far the hormonic effects of the sex 

 glands are direct or indirect. Further, the sexual gland may 

 influence the metabolism in a very complicated manner. This 

 may be illustrated by examples. It has long been known that 

 fat tends to accumulate in the castrated animal. One might 

 suppose that this is due to the absence of sex hormones as with 

 the other results of castration. But new experiments of 

 Heymans (1921) in Gley's laboratory show that a different 

 explanation is possible. Heymans measured the gaseous 

 exchange of cocks and capons, and, like other investigators, 

 found that the exchange in the capon is about 20 to 30 per cent, 

 lower than that of the cock. Heymans found further that the 

 gaseous exchange of normally developed cocks in which only 

 small fragments of testicular grafts were present is about 

 10 to 20 per cent, lower than that of the ordinary cock. Since 

 the accumulation of fat must be explained by the diminution 

 of the gaseous exchange, and since the latter is also diminished 



