THE MALE REPRODUCTIVE ORGANS. 989 



The spermatozoa are produced in enormous numbers. It is 

 calculated that at ejaculation each cubic centimeter of the liquid 

 contains from sixty to seventy 



millions of these cells. The * Primary 



adult ripe spermatozoon is 



characterized as an independ- 



ent cell by its great motility, 



due to the cilia-like contrac- 



tions of its tail. Its power of, 



movement or its vitality is 



retained under favorable con- * * Spermatozoa. 



di tionS for Very long periods. Fig. 306. -Schema to indicate the proc- 



J . ess of maturation of the spermatozoa. 



The most striking instance of (Bovert). 

 this fact is found in the case 



of bats. In these animals copulation takes place in the fall and 

 the uterus of the female retains the spermatozoa in activity until 

 the period of ovulation in the following spring. Even in the human 

 being it is believed that the spermatozoa may exist for many days 

 in the uterus and Fallopian tubes of the female. In the semen that 

 is ejaculated during coitus the spermatozoa are mixed with the 

 secretions of the accessory reproductive glands, such as the seminal 

 vesicles, the prostate gland, and Cowper's gland. The specific in- 

 fluence of each of these secretions is not entirely understood, but 

 experiments show that in some way they are essential to or aid 

 greatly in maintaining the motility of the spermatozoa. Steinach * 

 has found, for example, that removal of the prostate gland and 

 seminal vesicles in white rats prevents successful fertilization of the 

 female, although the ability and desire to copulate are not inter- 

 fered with. This result has been corroborated by Walker, f Accord- 

 ing to this author, removal of both the prostate and seminal vesicles 

 in the rat leaves the testes in apparently normal condition, but the 

 animals are not able to fertilize the female. Removal of the testes, 

 on the other hand, prevents the development of the prostate in the 

 young animal and causes atrophy of the gland in the adult. Evi- 

 dently, therefore, the testis controls, in some way, probably by a 

 hormone, the metabolic processes in the prostate. Walker believes 

 that the prostatic secretion aids in rendering the spermatozoon 

 properly motile. The secretion of the seminal vesicles in the rat 

 exhibits a curious property of clotting upon mixture with the 

 secretion of a small gland at its base the coagulating gland. If 

 the secretion of the vesicles follows the ejaculation of the semen, it 

 is possible that the coagulation of the former serves to occlude the 



* See Steinach, "Archiv f . die gesammte Physiologic," 56, 1894, and Walker, 

 "Archiv f. Anatomie u. Physiologic," 1889, p. 313. 



f Walker, "Johns Hopkins Hospital Reports," 16, 1911, and "Johns Hop- 

 kins Bulletin," 21, 1910. 



