THE REPRODUCTIVE ORGANS. 107 



i. The cloaca is the terminal portion of the large 

 intestine, into which the ureters and the bladder 

 open. 



ii. The bladder is a thin-walled bilobed muscular sac, 

 lying on the ventral surface of the large intestine 

 and cloaca, its two lobes communicating freely 

 with each other. It is invested by peritoneum 

 and attached to the sides of the body by special 

 peritoneal folds. 



Innate the bladder with a hlow-pipe inserted through the cloacal 

 aperture: pass a seeker up the cloaca to determine the exact position 

 of the opening from the bladder to the cloaca. Cut up the cloaca 

 along one side: wash out its contents and examine the opening into 

 the bladder. 



iii. The ureter or vas deferens is continued behind 

 the vesicula seminalis as a very short tube, open- 

 ing into the dorsal wall of the cloaca almost 

 exactly opposite the opening of the bladder on 

 the ventral surface. The openings of the two 

 ureters are close together on the apices of two 

 small papillae, overhung by a slight valvular pro 

 jection of the mucous membrane of the cloaca. 



iv. Remove a small piece of the testes : place it on a slide 

 in a drop of salt solution: press it slightly: cover and 

 examine with a high power to see the spermatozoa. 



B. The Female Frog. 

 1. The Eeproductive organs. 



Dissect as in the male. 



i. The ovaries are a pair of black masses lying in folds 

 of the peritoneum ventral to the kidneys, in very 

 much the same position as the testes in the male. 

 Their shape and size vary much at different 

 seasons of the year. On their surfaces are 

 - numerous rounded projections, like small shot ; 

 these are ova in various stages of development r 

 the smaller and younger ones are white ; the 

 larger and more mature ones black in one half, 

 and white or yellowish in the other. Each ovary 



