376 EXAMPLES OF CHEMICAL CORRELATION 



dent inflow of pancreatic juice and bile, the secretion of succus entericus 

 is greatly increased. According to some observers, however, this 

 increase is attributable to secretin, which is believed by them to 

 stimulate the intestinal glands as it does the glandular cells of the 

 pancreas. It is difficult at present to disentangle these alternative 

 possibilities, and further investigation is evidently required before the 

 relative parts played by secretin and the pancreatic juice itself in 

 promoting the secretion of succus entericus can be correctly evaluated. 



THE CHEMICAL CORRELATION OF THE ORGANS OF 

 GENERATION. 



The secondary sexual characters of the male, such as the growth of 

 the beard and the deepening of the voice in man, the development of 

 horns ia the ram and of the comb and tail-feathers of the cock, have 

 long been known to be attributable to the development of the Testes. 

 Castration has long been practised both in man and in animals for the 

 purpose of preventing the development of secondary sexual characters, 

 and of bringing about the psychic and metabolic modifications which 

 also accompany the excision of these organs. The removal of the testes 

 in man before the onset of puberty prevents the appearance of the 

 beard and the deepening of the voice which characterises that period 

 of development, and hardening of the epiphyses of the bones is delayed, 

 so that the legs and arms grow to an unusual length in proportion to 

 the size of the whole body. In certain varieties of sheep only the males 

 are possessed of horns, and in these varieties castration of the young 

 male altogether suppresses the development of the horns. Similarly 

 the castration of cocks suppresses the development of the comb. If, 

 however, the excised testicle be implanted in another part of the body, 

 as, for example, in the peritoneal cavity, then the secondary sexual 

 characters develop normally, the penis grows to its normal dimensions, 

 the seminal vesicles and the prostate develop as if the testes were 

 actually functioning as a generative organ, and yet, not only are the 

 testes prevented by lack of communication with the Vas Deferens from 

 discharging spermatozoa but, as a matter of fact, the spermatogenic 

 tissues of the testes dwindle away, and the production of spermatozoa 

 actually ceases. The effect of this organ upon the development of the 

 secondary sexual characters is therefore, evidently, not attributable 

 to its spermatogenic tissues, and appears to be due to the Interstitial 

 Cells which are normally present between the seminal tubules and 

 become increased in number in the transplanted organ. Since these 

 tissues are provided with no duct for the conduction of their products 

 to the exterior, the channel of transmission of the substances from the 

 interstitial cells, or, as Steinach calls them collectively " The puberty- 

 gland," to the tissues which they affect, can only be the general circu- 

 lating media, the blood and lymph. The puberty-gland is, in fact, an 

 example of the Ductless Glands, or Endocrine Organs. 



