366 DISSECTION OF THE RABBIT. 



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 

 turn them forwards with the testes and vasa deferentia. Deter- 

 mine the line of the pelvic symphysis and cut it through with 

 a strong knife placed exactly along the median line. Separate 

 the two halves. Note the corpora cavernosa, a pair of hard 

 ligamentous bodies running backwards 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. 



Clean 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 

 cavernosa. The free end of the penis is soft and 

 obliquely truncated ; and is invested by a loose 

 sheath of skin, the prepuce. The external aper- 

 ture of the urethra is a slit-like opening on its 

 posterior surface. 



