174 PHYLUM CHORD ATA 



closely to the openings of the ureters, and it can thus receive 

 the urine from them ; in it urine is stored. 



On the ventral surface of each kidney is an irregular, yellow- 

 ish line which is called the adrenal body, an endocrine body. 



The genital organs consist of the testes in the male and the 

 ovaries in the female, and the ducts which conduct the genital 

 products to the outside. 



The Male. The testes are two yellow, ovoid bodies which lie 

 against the ventral surface of the kidneys and are attached to 

 the dorsal wall of the abdominal cavity by mesenteries. Join- 

 ing each testis with the ventral surface of the kidney are about 

 a dozen fine tubules, which are suspended in the mesentery. 

 Through these the spermatozoa, which are formed in the testis, 

 make their way into the kidney and thence into the ureter. This 

 duct thus serves the double function of a ureter (an outlet for 

 urine) and a sperm duct (an outlet for sperm) and is thus a 

 urinogenital duct. 



Many male frogs have rudimentary oviducts, which appear as 

 a pair of slender white cords, each lying alongside the kidney. 



The Female. The ovaries differ very much in size and appear- 

 ance at different times of the year. In the springtime they are 

 often so distended with the small, spherical ova that they may 

 almost fill the abdominal cavity. Tf this is not their condition, 

 they appear as a pair of folded, dark-colored bodies which lie on 

 the ventral surface of the kidneys attached to the dorsal body wall 

 by median mesenteries. The paired ducts through which the ova 

 find their way to the cloaca are the oviducts. In adult females 

 each of these ducts is a thick-walled, twisted tube which lies in the 

 abdominal cavity against the dorsal body wall. Its anterior end 

 opens into this cavity and is situated at the side of the heart and 

 the posterior end opens into the cloaca. The posterior portion of 

 the oviduct is expanded and forms a uterus, a reservoir for ova. 



The ova escape from the ovaries by the rupture of their walls 

 into the abdominal cavity; they then make their way to the 

 mouths of the oviducts and through them into the cloaca. Dur- 

 ing this descent of the ova the albumen which surrounds them 

 is secreted by the walls of the oviducts. 



