THE HORMONES IN HUMAN REPRODUCTION 



In the various divisions of the animal kingdom there is a 

 vast array of secondary sex differences. The tail of the pea- 

 cock, the antlers of the stag, the beard and the smell of the 

 billy goat, are evidences of what Nature can do in this way. 

 The subject would fill a large book.^ Perhaps the most familiar 

 of all, the comb of Chanticleer, has been seized upon by the 

 experimenters (as we shall see) and has been made to tell us, 

 more than any other one sign, just how the hormones control 

 the secondary sex characters. 



THE HORMONE OF THE TESTIS 



People have known since prehistoric times that castration 

 of men and domestic animals suppresses the development of 

 secondary sexual characters and causes atrophy of the 

 accessory male sex organs, such as the seminal vesicles and 

 prostate gland. The gelding of stallions, the castration of 

 male calves to make steers, of cockerels to produce capons, 

 and even of boys for the production of eunuchs, has long been 

 practiced. If anyone asked how the testis can control the size 

 and form of the skeleton, the distribution of hair, or the tone 

 of the voice, the explanation was vaguely to the effect that 

 some sort of "sympathy" existed between the parts of the 

 body, with the implication that the nervous system is the con- 

 necting agent. In 1849, however, Arnold Adolph Berthold, a 

 physician and zoologist of Gottingen, proved once for all 

 that the influence of the testis is carried by something that 

 travels in the circulating blood. Berthold's little contribution 

 (it is only four pages long) belongs to the fundamental 

 classics of endocrinology.' He tells us that on August 2, 1848, 

 he castrated 6 cockerels, 2 to 3 months old. Their combs, 

 wattles and spurs were not yet developed. From two of them 

 the testes were completely removed. These became typical 



2 See many, chapters of Edgar Allen, Sex and Internal Secretions. 

 8 A. A. Berthold, "Transplantation der Hoden," Archiv fur Anatomie, 

 Physiologie, und Wissenschaftliche Medizin, 1849 (Appendix II, note 18). 



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