IX 



KIDNEYS 



into either a parallel or a divergent position. When they 

 are parallel the air, passing to and from the lungs, sets their 

 edges in vibration and gives rise to the characteristic croak, 

 the pitch of which can be slightly altered by stretching or 

 relaxing the cords. 



Structure of the Kidneys. The form and situation of the 

 kidneys (Figs. 3, 4, 5, and 7, kd) have already been referred 

 to. Each is a flattened organ of a deep reddish-brown 

 colour, its inner edge nearly straight but for one or two 

 notches, its outer edge curved. Its ventral face is covered 



ur.tu 



m.cfi 



per' 



nst 



FIG. 46. Transverse section of frog's kidney. 



gl. glomerulus ; ;//. cp. Malpighian capsule ; nst : nephrostome (see p. 98 and Part II) ; 

 Per. peritoneum covering ventral face of kidney ; per' . fold of peritoneum sup- 

 porting its outer border ; per", fold supporting its inner border ; Ur. ureter ; 

 ur. tu. urinary tubules. (After Marshall and Bles.) 



by peritoneum (Fig. 46, per\ continued on the one hand 

 into the parietal layer (Fig. 5, /. per), of that membrane, on 

 the other into the mesentery (mes) ; its dorsal face is bathed 

 by the lymph of the sub-vertebral sinus (sv. fy. s). From the 

 posterior end of its outer edge a delicate tube, the ureter 

 (Figs. 3, 4, and 7, ur), passes backwards and opens into the 

 dorsal wall of the cloaca. On its ventral face is a singular 

 yellowish-white stripe, the adrenal body, an organ of im- 

 perfectly-known function (Fig. 7, between the lines from 

 kd and ts\ 



PKACT. ZOOL. L 



