348 



SPLANCHNOLOGY. 



its anterior edge contains tlie spermatic artery and veins ; it 

 extends from the inguinal canal to the testicle, certain coverings 

 being common to it and the latter. 



The serous covering of both structures is continuous with the 

 peritoneum, and consists of two folds, the parietal layer being 

 attached to the infundibuliform fascia, the visceral layer to the 

 duct, vessels, and other structures which help to form the cord. 

 The artery of the cord supplies the spermatic cord with blood. 



The male genital glands, or testicles, are two oval, compound 

 tubular glands, situated in the scrotum, and attached superiorly 

 to the spermatic cord ; their long axes are 

 placed almost horizontally from before back- 

 wards. In foetal life they are at first situ- 

 ated in the abdominal cavity, behind the 

 kidneys, and above the peritoneum. At a 

 certain period they descend through the 

 inguinal canals into the scrotum. In their 

 descent each is guided by a soft cord, the 

 guhernaculum testis or pilot, which at first 

 joins them to the abdominal floor, in their 

 descent through which they, and the sperm- 

 atic cord, carry with them coverings de- 

 rived from the tissues forming the abdo- 

 minal parietes. 



Thus from without inwards, the scrotum 

 is derived from the skin ; the dartos from 

 the abdominal tunic ; next the spermatic 

 fascia, very rudimentary in the horse, and 

 especially about the testicle, is derived from 

 the external oblique ; then the cremasteric 

 fascia, perhaps from the internal oblique ; then the infundi- 

 buliform fascia from the fascia transversalis ; and finally, two 

 serous folds from the peritoneum, forming a shut sac, continuous 

 in the domesticated mammals with that of the abdomen. The 

 remaining coverings of the testicle are peculiar to itself. 



The outer serous covering of the testicle is called the tunica 

 vaginalis reflexa, which is united by cellular tissue to the infundi- 

 buliform fascia ; the inner, the tunica vaginalis 2Jro2')via, is 



Exterual view of li.i^ht 

 testicle of horse. a, Tes- 

 ticle; 6, Globus major of 

 epididymis ; V , Globus uiiuor ; 

 c, Fold of tuuica propria 

 reflected from testicle to epi- 

 didymis ; d, Spermatic cord ; 

 e, Vas defereus ; /, Spermatic 

 artery. 



