24 CHARLES F. W. McCLURE 



definite direction and in a continuous flow when skin gloves 

 filled with Ringer's solution approximately isotonic with 

 frog's blood are suspended in the same solution either at a 

 constant temperature or at different temperatures. Also, 

 when fluctuations in the weight of the glove occur, in the sense 

 that the latter loses or gains weight in relation to differences 

 in temperature, we have seen that the fluctuations appear to 

 occur more readily in skins whose power to transport water 

 through them in opposition to osmotic pressure either is lost 

 or has become greatly diminished. If, therefore, by means 

 of experiment we can eliminate the continuous transport of 

 water through the skin in opposition to osmotic pressure, and 

 if a gain or a loss of water by the glove then occurs, this 

 must be due to the absorption or to the loss of water by the 

 skin itself. When formaldehyde is added both to the Einger's 

 solution placed in the glove and also to the solution in which 

 the glove is suspended, it has been found that the power of 

 the skin to transport water through itself in opposition to 

 osmotic pressure either is completely lost or is greatly 

 diminished. 



Two skin gloves removed from the right and the left hind 

 legs of the same individual (R. pipiens) were used in the 

 following experiments (experiments 466 and 466 A, fig. 9). 

 The right skin glove, the control (exper. 466 A), with the 

 outside of the skin turned outward, was filled with Ringer's 

 solution approximately isotonic with frog's blood and was 

 suspended alternately at 15C. and 25C. in the same solution. 

 The behavior of this glove was typical of that observed in 

 other similar experiments (fig. 2), where water was trans- 

 ported through the skin continuously. 



The left skin glove (exper. 466, fig. 9) of the same frog, 

 also with the outside of the skin turned outward, was filled 

 with a 5 per cent solution of formaldehyde made up with 

 Ringer's solution approximately isotonic with frog's blood, 

 and was then suspended alternately at 15 C. and 25 C. in the 

 same solution. In this case the behavior of the glove differed 

 markedly from that of the control; the glove did not gain 



