The Pern's 



15 



Thus it occurs that the protrusion and retraction of the 

 penis are brought about in a different manner in the horse 

 from that observed in ruminants and swine. The penis of 

 the soliped is protruded chiefly through an elongation of 

 the organ itself in the process of erection ; the penis of the 

 ruminant is protruded largely through the elimination of the 

 S-curve and temporary lengthening of the retractor penis 

 muscle. 



Fig. 9— Penis of Calf with. Sheath forcibly Everted showing 

 Unopened Preputial Sac. x 3. 

 Ps, Preputial sac. Other lettering same as in Fig. 8. 



4. The Sheath and Prepuce 



Veterinary anatomists commonly use the words "sheath" 

 and "prepuce" as synonomous terms. When studying the 

 diseases of the genital organs, it is preferable to different- 

 iate the sheath and prepuce as two separate structures of 

 different embryologic history. It will simplify the study of 

 the pathology of these structures if the prepuce is regarded 

 as that sac which reaches from the fornix, or base of the 

 glans, to its apex when the organ is at rest. The sheath 

 begins at the apex of the penis, when the organ is at rest, 

 and extends forward to the exterior opening where it be- 

 comes continuous with the general integument. The pre- 



