CHARLES F. W. McCLURE 263 



ously absorbed through the integument in both larval and adult frogs 

 and toads when the latter are allowed to remain in such media, and 

 that the excess of fluid taken into the body in these cases is normally 

 eliminated by the kidneys. Since the water taken into the body by 

 absorption through the integument must necessarily reach the kid- 

 neys by way of the vascular system, the possibility suggests itself 

 that the edematous condition of the frog larvse referred to may be 

 due to the deficiency observed in the development of certain specified 

 tubules of the kidney, or, in other words, to a block in the normal 

 kidney function. In consequence of this an excess of water which 

 is constantly being taken into the body through the integument is re- 

 tained in the body, since it can no longer be eliminated by the kid- 

 neys. That this is actually the case, as far as these particular frog 

 larvae are concerned, seems to be borne out by experiments on adult 

 frogs and toads in which an edematous condition of the body can be 

 produced by ligation of the ureters. 



The distal ends of the ureters in the frog and toad lie in the dor- 

 sal wall of the cloaca and open dorsally into the latter independently 

 of the bladder, which opens on the ventral wall of the cloaca. It 

 is therefore not a difficult matter to ligate the ureters by means of 

 artery forceps and small metal clamps, or to pass a ligature around 

 the ureters which can be tied over the urostyle. In such cases neither 

 the bladder nor the outlet of the intestinal canal through the cloaca is 

 interfered with. 



Among 53 ligation experiments thus far made by the writer, chiefly 

 on adult toads, the six mentioned in Table I illustrate the range 

 of results obtained. In all cases the toads^ were kept in water for 

 a considerable time and weighed at intervals before applying the 

 ligature. This was done in order to establish a normal balance, 

 under such conditions, between the absorption of water through the 

 integument and its elimination from the body by the kidneys. 



The first figure in each of the columns of Table I (Experiments 1 

 to 6) indicates the weight of the toad in gm. at the time the ureters 

 were ligated and before the toad was again placed in water. The 

 succeeding figures in each column indicate the observations made at 

 different intervals of time. 



^ Bujo lentiginosus Shaw. 



