176 THE EXTERIOR OF THE HORSE. 



thickening which marks the median line, from the sheath and the 

 testicles, or the mammae, to the anus. It is shown in the form of 

 a small crest, more or less prominent according to the subjects, 'is 

 a simple peculiarity of the regions upon which it is observed, and, 

 therefore, is devoid of all interest. 



CHAPTER VI. 



GENITAL ORGANS. 



THE examination of the genital organs should not be neglected, 

 either for the purpose of ascertaining their good conformation in ani- 

 mals which are destined for reproduction, or for simply proving their 

 state of health or of disease. 



1. GENITAL ORGANS OF THE MALE. 



These comprise, with respect to the exterior, the testicles and the 

 penis, to which are annexed the protecting coverings, dependencies of 

 the integument, known under the name of enveloping tunics for the 

 former and sheath for the latter. 



A. The Testicles and their Enveloping Tunics. 



The organs which secrete the semen, the reproductive fluid of the 

 male, are two glands, situated on each side of the median line, in the 

 inguinal region, and between the thighs. They constitute, as a whole, 

 an irregularly-rounded mass, divided in its middle into two almost 

 equal lobes, by a slight groove, a sort of raph6, which behind is con- 

 tinuous with the perinea! raphe, and in front is prolonged upon the 

 inferior surface of the sheath. 



1st. The Enveloping Tunics. The testicles are surrounded by several 

 superposed envelopes, which are, proceeding from the superficial to the deep 

 parts : 



a. The scrotum, or the skin (but the whole double sac, composed of all the 

 enveloping tunics, is also spoken of as the scrotum). 



b. The dartos, very adherent to the latter, and forming for each testicle an 

 independent musculo-elastic sac. 



c. The sub-dartoid connective tissue, a more or less dense layer, which separates 

 the dartos from the following tunic. 



d. The cremaster or tunica erythro'ides, a striated muscle which is attached to 



