THE MALE HORMONE 



tion of the warm-blooded condition was accomplished, Nature 

 discovered (so to speak) that after all the testes could not 

 stand the temperature at which she had stabilized the mam- 

 mals, and had to get them to a cooler place; but any such 

 conjecture seems to put Nature (or whatever you choose 

 to call the forces that guide evolution) in a position like 

 that of tariff legislators, chess players and others who find 

 that one change in a complicated situation may set off un- 

 expected changes elsewhere. At any rate, descent of the 

 testes is a deep-seated phenomenon that has become essential 

 to fertility. The inside of the scrotum is several degrees 

 cooler than the abdominal cavity, because the scrotal sac 

 has thin walls and no insulating layer of subcutaneous fat, 

 but numerous sweat glands by which it loses heat. Moore 

 found that if he put the testis of a guinea pig or other animal 

 back in the abdominal cavity (preserving its blood supply) 

 and stitched it there, the seminiferous tubules became dis- 

 organized within a week, but recovered if he brought them 

 down again before the damage had become permanent. He 

 took also a fertile ram and wrapped its scrotum in woolen 

 coverings so that the testes were brought to the temperature 

 of the rest of the body. This too caused cessation of sperm 

 production. Actual direct heating of the testis has a similar 

 effect. A single exposure of the guinea pig's testis for 15 

 minutes to a temperature 6 degrees above that of the interior 

 of the body causes degeneration of the seminiferous tubules. 

 It is known that in man high fevers are followed by temporary 

 loss of spermatozoa. 



Descent of the testis into the scrotum is part of the gen- 

 eral pattern of the development of the sex gland and is 

 therefore subject to control by the pituitary and pituitary- 

 like hormones. It has been known for about 10 years that 

 gonadotropic hormones from pregnancy urine can be used 

 for the treatment of non-descent of the testis in boys. It does 

 not always succeed, for adhesions and other obstacles may 



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