40 CHARLES F. W. McCLURE 



First, experiments were made to determine what role the 

 element K generally plays in influencing the velocity of diffu- 

 sion of water through frog skins taken from different animals 

 of the same and of different species. After this had been 

 determined, special type experiments were made on skin 

 gloves, with the outside of the skin turned outward as well 

 as inward, in which the conditions were modified in various 

 ways, as regards the presence and absence of K in the 

 Ringer's solution contained in the glove and in the solution 

 in which the glove was suspended. 



Experiment 433 (fig. 15) 



The right and the left skin gloves of the same frog (R. 

 pipiens), with the outside of the skin turned outward, were 

 first filled, respectively, with Ringer's solution approximately 

 isotonic with frog's blood and with Ringer minus K, and 

 were then suspended in Ringer's solution. (Diagrams A and 

 B in fig. 15 illustrate the type of the experiment, as regards 

 the character of the Ringer's solution in the glove and that 

 of the Ringer in the container in which the glove was sus- 

 pended. ) During the course of twenty-two hours ' suspension, 

 the right glove, which contained Ringer, and which in this 

 instance served as the control (Dext. A, first day], gained 

 more in weight than did the left glove which contained Ringer 

 minus K (Sin. B, first day, fig. 15). At the end of twenty-two 

 hours, the right glove was filled with Ringer minus K, instead 

 of Ringer (Dext. B, second day], and the left glove with 

 Ringer, instead of Ringer minus K (Sin. A, second day, fig. 

 15), and again both gloves were suspended in Ringer for 

 another period of twenty-two hours. Figure 15 shows graphi- 

 cally that, during the second day's suspension, the left glove 

 containing Ringer in which K was present (Sin. A, second 

 day] gained more in weight than the right glove in which K 

 was absent (Dext. B, second day). The behavior of the con- 

 trol on the first day (Dext. A, first day) signifies a marked 

 capacity of the skin of this particular frog to transport water 

 through itself under conditions in which both surfaces of the 



