Sterility of the Male Animal 123 



the secretions of the other glands. In the pig, there are two pros- 

 tates, while, in the dog and cat, there is one large gland com- 

 pletely surrounding the urethra. 



Cowper's glands are also acinous in character. Chauveau states 

 they are absent in ruminants, but Zschokke claims they are pres- 

 ent. They are absent in the dog, but present in the cat. 



The phy.sical characters of the secretions from the seminal ves- 

 icles, prostate and Cowper's glands varies somewhat, is chiefly 

 of a clear, watery character, that from the Cowper's glands being 

 somewhat more viscid. They are neutral in reaction. 



The function of the .secretions from these subsidiary glands 

 has not been very accurately determined, but they apparently 

 serve a useful purpose as lubricants and, still more, they dilute 

 the secretions from the testicles, adding volume to the semen and 

 giving a wider dissemination to the spermatozoa. Furthermore, 

 it is believed that their presence invigorates the spermatozoa. 



The .semen, at the time of ejaculation, consists of an admixture 

 of the secretions from these acces.sory glands, with the spermato- 

 zoa and accompanying fluids from the testicles. It is a whitish, 

 viscid fluid of feeble alkaline reaction, and has a specific odor. 



The spermatozoa in this fluid show very vigorous motion, in- 

 duced by the contractions of the tail, which cause a progressive 

 movement comparable to that of a fish or an eel. Hensen states 

 that they may move 1.2 to 3.6 mm. per minute. Their vigor is 

 greatest at about the body temperature and is decreased or stop- 

 ped by heat or cold or by the addition of water, acids, metallic 

 salts, etc., while the vigor of the movements is increa.sed by the 

 addition of weak alkalies, blood serum and estrual di.scharges. 



The commencement of the secretion of spermatozoa marks the 

 age oi puberty in the male and is expressed by the appearance of 

 sexual desire. Its advent varies greatly according to species, in 

 the horse from 10 to 18 months, in the bull from 8 to 10 months 

 and in most other species, at an earlier date. 



The amount of semen ejaculated during a single coition has 

 not been well determined. In the bull, it is 5-6 c m.' (Zschokke) 

 and contains more than 60,000 spermatozoa per mm.' 



In order that successful copulation may occur, it is essential 

 that the testicles, excretory ducts, urethra, penis and acce.s.sory 

 glands be normal in structure and function, and that the locomo- 

 tory apparatus be sufficiently normal to enable the male to mount 



