THE MALE GENITAL ORGANS 247 



(g) The spermatic vein (v. spermatica) is formed by a net- 

 work of vessels, the plexus pampiniformis, which surrounds 

 the internal spermatic artery as it approaches the testis. 

 The left vein opens forwards into the inferior caval at the 

 angle formed by the latter with the renal artery. That of 

 the right side enters the inferior caval at about the level 

 of the spermatic arteries. 



Owing to the open communication of the testis sac with the ab- 

 dominal cavity, the association of the ductus deferens with the sper- 

 matic vessels to form a spermatic cord (funiculus spermaticus) as in 

 the human species is very imperfectly expressed. 



2. The structure and attachments of the penis should be examined. 

 Apart from the urethra, the soft-walled tube which traverses 

 it ventrally and opens at its tip, the body of the penis is formed 

 chiefly by a pair of hollow fibrous structures, the cavernous 

 bodies (corpora cavernosa penis). 



The cavernous bodies have thick white sheaths (tunicae albu- 

 gineae) which fuse in a median septum and surround columns of spongy 

 tissue which can be distended with blood i.e. erectile tissue. The fusion 

 of the sheaths produces an apparently unpaired, median structure and 

 the two contained corpora are best seen by cutting the penis transversely 

 after the study of the organs has been otherwise completed. The wall of 

 the associated portion of the urethra has a thin layer of similar erectile 

 tissue. 



The cavernous bodies diverge at their proximal ends, the 

 diverging parts constituting the crura penis, and each crus is 

 firmly attached to the ventromedial margin of the ischium, a little 

 posterior to the symphysis, by a short cord of -white fibrous con- 

 nective tissue. 



The crus is partly concealed by a short thick ischiocavernosus 

 muscle, the origin of which is on the edge of the ischium both 

 anteromedial and posterolateral to the attachment of the crus. 

 The penis is also attached to the symphysis by a short but stout 

 unpaired suspensory ligament (lig. suspensorium) and by a thick 

 spindle-shaped pubocavernosus muscle lying in a median position 

 ventral to the ligament and between the two ischiocavernosi. 



Strictly speaking, a glans penis, which occurs in many mammals, 

 is absent in the rabbit and the free extremity of the organ, occupying 

 the position of that part, should be called simply pars libera. The 

 glans, properly, is a swollen terminal portion of the erectile tissue 

 (corpus spongiosum) in the wall of the urethra. 



