22 THE BREEDING OF ANIMALS 



stance of the testis is composed of the convoluted seminif- 

 erous tubules, two or three of which join together to 

 form a straight tubule which passes into the body of 

 the mediastinum. The straight tubules within the 

 mediastinum unite in their turn, giving rise to a network 

 of vessels called the rete testis. From the rete the vasa 

 efferentia are given off. Between the tubules is a loose 

 connective tissue containing a number of yellow epithelioid 

 interstitial cells. The connective tissue also contains 

 numerous lymphatics and blood-vessels (branches of the 

 spermatic artery). The nerves of the testis are derived 

 from the sympathetic system, but a few filaments come 

 from the hypogastric plexus." 



The male reproductive organs 1 other than the testicles 

 are chiefly concerned in providing for the transmission of 

 the fully mature sperm-cells from the testicles. The 

 seminal fluid is secreted by the seminiferous tubules and 

 after expulsion is mixed with other fluids from the male 

 accessory organs. 



The function of the seminal fluid seems to be to pro- 

 vide a favorable medium for the spermatozoa. 



24. Castration. The removal of the testicles of the 

 male results in profoundly influencing not only the breed- 

 ing function of the animal but in marked bodily change. 

 While the testicles seem to have no important connec- 

 tion with or relation to the body-cells and their removal 

 interferes in no way with the normal, healthy function- 

 ing of the other bodily organs, it is nevertheless true that 

 castration materially influences the animal economy. 



1 The student is referred to standard works on anatomy and 

 physiology for a detailed discussion of the organization and 

 functional relations of the various male reproductive organs. 

 See Sisson, "Veterinary Anatomy." 



Chauveau, "Veterinary Anatomy." 



