18 CHARLES F. W. MCCLUKE 



glove through the skin outward. In other words, if the skin 

 itself did not at first absorb and hold water, the glove would 

 probably begin to lose weight immediately when suspended 

 in Ringer's solution. It is therefore evident that at the 

 start at least two separate factors acting in opposition to 

 each other are involved in the behavior of skin gloves, with 

 the inside of the skin turned outward, when filled with 

 Ringer's solution isotonic with frog's blood and suspended in 

 the same solution. One of these factors is the capacity of 

 the skin itself to absorb and to hold water, and the other, the 

 power of the skin to transport water through itself, when the 

 skin is bathed on both surfaces by solutions having the same 

 osmotic pressure. While both factors may act simultane- 

 ously, the action of one may mask or overbalance the other, 

 so that, even though w^ater is transported through the skin 

 outward when the glove is first placed in Ringer's solution, 

 the glove will not begin to lose weight until the hydration 

 capacity of the skin has been satisfied and an equilibrium in 

 this respect has been established or, until the rate of absorp- 

 tion of water by the skin is exceeded by that at which water 

 is simultaneously transported from the glove through the 

 skin outward. 



We have already seen that, when the outside of the skin 

 is turned outward, the rate at which water is transported in- 

 ward through the skin varies greatly in different cases (figs. 

 1, 2, 3, and 4). The same may be said concerning the rate at 

 which water is transported outward through the skin when 

 the inside of the skin is turned outward. We now pass to 

 the consideration of a number of experiments which illustrate 

 the behavior of skin gloves with the inside of the skin turned 

 outward, when filled with Ringer's solution approximately 

 isotonic with frog's blood and suspended in the same solution. 



Experiments 409 and 412 (fig. 6) illustrate the behavior of 

 skin gloves removed from the hind legs of two different 

 frogs (R. pipiens) which had been kept in the laboratory 

 during Jhe winter prior to the experiments. The frogs were 

 active, but their skin was pale and dull in color. In each 



