36 CHARLES F. W. McCLURE 



Experiment 15 (table 9). Three experiments were made by feed- 

 ing adult frogs with solutions of trypan blue of low concentration. 

 In one extreme case (Exp. 15) a frog was fed sixteen times in the 

 course of ten days but no indication of vital staining was observed 

 in any of the typical tissues. 



In all of the remaining experiments solutions of high concen- 

 tration were used. 



Experiments 16 and 17 (table 9). In two experiments (16 a and 

 17 a) in which the duration of the experiment was limited to one 

 and three days respectively, and the number of feedings few, no 

 vital staining was observed in any of the tissues. 



In all of the remaining experiments, however, some or all of 

 the typical tissues of the body were found to store the dye. The 

 essential feature noticed in connection with these feeding experi- 

 ments was that the stellate cells of the liver were invariably found 

 to store the dye prior to the epithelium of the kidney tubules. 

 In Experiments 16 d and 17 b dye was stored in the stellate cells of 

 the liver, but not a trace was observed in the epithelium of the 

 tubules in the kidney. In Experiments 16 b, 16 c, 17 c, 17 d and 17e 

 a relatively large amount of dye was typically stored in the liver, 

 while a mere trace only was found in the epithelium of the kidneys. 

 Irrespective of the amount present, in every one of the above- 

 mentioned cases the amount of dye stored in the stellate cells of 

 the liver was invariably in excess of that found in the epithelium 

 of the tubules in the kidney. 



In Experiments 17 e and 17 f, although dye was stored in the 

 liver in excess of that found in the kidney, the amount stored in 

 the liver was by no means as large as one might expect in cases in 

 which the experiment had been so extended. The general impres- 

 sion one gets is that absorption by the mucosa is not a uniform and 

 progressive process and that the ability of the mucosa to absorb 

 the dye differs considerably among different individuals. This is 

 well shown by a comparison of Experiment 16 d with Experiments 

 16 b and 16 c. In Experiment 16 d not a trace of dye was found in 

 the epithelium of the kidney, while in Experiments 16 b and 16 c 

 a few dye granules were observed (table 9). In cases where the 

 number of feedings was considerable and the duration of the experi- 



