CHAPTER XX. 



GENERATION AND DEVELOPMENT. 



The seminal fluid is secreted by the testicle, and constitutes 

 the fecundating material of the male. As discharged 

 from the urethra, it is mixed with the secretion of the 

 prostate and vas deferens. It is not known what part the 

 accessory secretions play, but they appear to be essential to 

 fertility. 



The spermatic fluid is alkaline or neutral in reaction, of 

 gelatinous consistence, and was found by Lassaigne, who 

 examined the material taken from the vesiculte seminalis of 

 the horse, to contain a large quantity of water, an abund- 

 ance of a substance termed by him spermatin, mucus, soda, 

 chloride of sodium, and phosphate of lime. Colin describes 

 the spermatic fluid of a bull after standing to consist of 

 two parts — the upper colourless and transparent, the lower 

 stratum milky and opaque. He regards the former as 

 prostatic fluid, the latter as spermatic. More recent 

 analyses of this fluid show it to contain serum and alkali 

 albumin, nuclein, lecithin, cholesterine, fat, leucin, tyrosin, 

 kreatin, inosit, sulphur, alkaline earths, and phosphates. 



The essential element of the spermatic fluid is the 

 spermatozoa, without which the fluid is not fertile. They 

 are developed in the seminal tubes of the testicle from 

 the so-called spermatoblasts. These are projections from 

 the wall of the tube, which, when ripe, leave the wall, 

 and are carried along in the fluid. They exhibit spontaneous 

 movement, the long tail moving from side to side, by which 

 means the organism is propelled when placed in the body 



