52 ELEMENTARY BIOLOGY. [CHAP. 



move the alimentary canal between the base of the 

 oesophagus and posterior third of the large intestine. 

 Next open up the latter, as directed in Sect. D. 4 ; wash 

 and examine under water. 



1. In both sexes. 



a. The kidneys ; symmetrically disposed on opposite 

 sides; relatively largest in the male. Each is 

 convex dorsally (outer border), incompletely lobed 

 on its inner border. 



b. The adrenal body ; a. band of yellow tissue running 

 along the ventral face of each kidney. 



c. The duct — ureter (female) or genito-urinary canal 

 (male) — running from the outer side of the pos- 

 terior part of each kidney to the cloaca. Open 

 the cloaca and pass a bristle into one of their 

 openings. 



In the male R. esculenta each duct is somewhat 

 dilated after leaving the kidney : it then narrows 

 again and opens on the dorsal wall of the cloaca 

 by an oblique slit with sharply defined edges. 

 In R. temporaria the duct does not dilate, or only 

 very slightly ; but on its outer side lies a glandular 

 mass (vesicula seminalis), from the inner side of 

 which a number of minute ducts open into the 

 genito-urinary canal. The aperture of the latter 

 in the cloaca is round and has tumid edges. In 

 the female of both species the ureters are very 

 slender. 



d. The bladder; (cf. Sect. D. 4. c.) 



2. In the female. 



a. The genital glands (ovaries) (cf. Sect. B. 2. h. yS.) ; 

 varying much in size with the season of the year. 



