CHAPTER IX 



THE MALE HORMONE 



THE male sex glands (testes) of man and the other 

 mammals, like the ovaries, perform a double task. 

 They exist primarily, of course, to produce the male 

 germ cells. In primitive aquatic animals this is all they need 

 to do. The Hydra, for example, shown in Plate II, C, in the 

 act of discharging its sperm cells directly into the v/ater, has 

 fulfilled its reproductive task for the season, and its empty 

 testes are of no more consequence than a spent skyrocket. In 

 mammals, however, things are not so simple. There are other 

 needs that can be fulfilled only by the coordination of various 

 parts of the body by means of a hormone. Not only must the 

 sperm cells be formed and ripened ; they must also be stored 

 until they are needed in mating. What is more, they must be 

 stored in a most particular way, immersed in a watery en- 

 vironment, for the mammals have never fully shaken off their 

 ancient adaptation to the sea. They spend their lives on land, 

 but when the time comes to reproduce their kind, their spawn- 

 ing requires salt water — not indeed the actual sea, but the 

 internal fluids of the generative organs. The egg ripens in the 

 fluid of the Graafian follicle. The sperm cells accomplish their 

 tortuous journey to the Qgg by swimming, and the offspring 

 of all the mammals spend the long term of gestation in a sub- 

 marine environment. You and I cannot remember our ances- 

 tral life in the water, nor the nine months we ourselves lived 

 beneath the chorio-amniotic sea, but our tissues recall it ; the 

 skin, the kidneys and the adrenal glands working to hold 

 sufficient water and just enough salt, the testes providing 

 through their accessory organs those fluids in which the sperm 

 cells may be effectually launched upon the sea of life. 



In another way also the endocrine function of the testis 

 becomes necessary. The higher animals lead complicated lives. 



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