ix KIDNEYS 145 



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 character- 

 istic 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 



ur.tu 



m.cft 



Ur 



jber* 



71 St 



FIG. 46. Transverse section of Frog's kidney, (x 45.) 



gl. glomerulus ; m. cp. Malpighian capsule ; nst. nephrostome (see pp. 98 and 

 601) ; per. peritoneum covering ventral face of kidney ; per', fold of peritoneum 

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

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



is covered by peritoneum (Fig. 46, per), continued on the 

 one hand into the parietal layer (Fig. 5, p. 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. ly. 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 cloaca in its dorsal wall. 

 On its ventral face is a singular yellowish-white stripe, 

 the adrenal body, an organ of imperfectly known function 

 (Fig. 7, between the lines from kd and ts). 



PRACT. ZOOL. T 



