356 DISSECTION OF THE BABBIT. 



its course is sinuous, but further forwards it 

 becomes straighter. 



The vasa deferentia 'are the modified Wolffian 

 ducts of the embryo. 



Dissect both scrotal sacs from the abdominal wall, and 

 tivrn them forwards with the testes and vasa deferentia. 

 Determine with the finger the boundaries of the pubes and 

 ischia. Cut longitudinally through the muscles ventral to the 

 /pelvis, aboM half an inch from the middle line on each side, 

 and down to the bone. Scrape clean the descending rami of 

 the pubes and ischia, and cut through them ivith bone-forceps 

 in front of, and behind, the obturator foramen on each side. 

 Bemove the pelvic symphysis, which is now isolated ; carefully 

 dissecting it from the underlying parts. Note the corpora 

 cavernosa, a pair of hard ligamentotis bodies running back- 

 wards from the hinder border of the ischia to the penis ; and 

 cut them across close to the ischia. 



Inflate the bladder and urino-genital canal by means of 

 a blowpipe inserted into the terminal aperture of the penis, 

 and tie a ligature round the penis half an inch from its end, 

 to prevent the air escaping. 



Glean the various structures in the order given below. 



e. The urethra, or urino-genital canal, is the continua- 



tion backwards of the neck of the bladder through 

 the pelvic cavity. It is a straight tube, with thin 

 and very vascular walls, and lies immediately 

 dorsal to the pelvic symphysis, and ventral to the 

 rectum. Behind the symphysis it is continued 

 into the penis. 



f. The penis is an elongated body, projecting from the 



ventral surface of the animal, immediately behind 

 the pelvic symphysis and in front of the anus. 

 It is traversed by the urethra, through which 

 the urinary and genital products are discharged. 

 The posterior wall of the penis is very vascular, 

 and forms the corpus spongiosum; while its 

 anterior surface is stiffened by the corpora 



