SEMEN. 



207 



The only carnivorous animal whose milk has been analyzed is the 

 bitch. Her milk has an acid reaction (when she is fed on animal 

 food), and contains 274.6 to 224.8 in 1,000 of solid constituents. Of 

 these, 80 to 110 are caseine, from 68.4 to 109.5 are butter, while the 

 quantity of sugar of milk is very small. The last and the butter 

 are increased by mixed food. The great amount of caseine and of 

 fat deserves especial notice, in a physiological point of view. 



II. SEMEN. 



Semen, as usually observed, is mixed with the prostatic fluid and 

 that secreted by Cowper's glands and the vesicula? seminales. It 

 can be obtained in its pure state only from the vasa deferentia and 

 the testes of animals in heat. When mixed as just stated, it is a 

 mucous, viscid, colorless fluid, considerably heavier than water, and 

 of a neutral or slightly alkaline reaction. 



1. The liquor seminis, a great part of which is derived from Cow- 

 per's glands, the prostate, and the vesiculse seminales, gelatinizes 

 after emission; the gelatinizing substance (spermatine) resembling 

 mucus more than fibrine. 



The salts most abundant in it are the phosphates of lime and 

 magnesia. The fat (p. 78) exists principally in the cells hereafter 

 to be described. Yauquelin found 10 per cent, of solid constituents 

 in the semen viz., 6 per cent, of organic matter, 3 of earthy phos- 

 phates, and 1 of soda. 



2. The peculiar histologi- 

 cal element of the semen, 

 the spermatozoids* (spermatic 

 filaments), are the most sin- 

 gular developments in the 

 organism. They occur in 

 the semen of all animals, 

 and are analogous in form 

 in all, though distinguish- 

 able in each species, as a 

 general rule; consisting of 



a round, OVal, Or pyriform Human spermatozoids. A. From the vas deferens : 1 to 



-IT i-i i n-i "*t their variety of character ; 5, seminal granules. B. 



DOdy, tO WhlCh a long tla- From testis . a> large cell; 2, same, containing three 



ment Or tail, gradually ta- S ranular todies, from which the spermatozoids are 



. . . ,11 developed ; 3, a bundle of spermatozoids still grouped 



penng to a point, is attached, together. 



Fig. 116. 



From <r7rspf*a, semen, , animal, and eTJof, resemblance. 



