32 CHARLES F. W. MCCLURE 



weight suggests that, after the hydration capacity of the skin 

 had been satisfied, there was set up an osmotic transfer 

 which continued either until an equilibrium had been estab- 

 lished or until the driving force of osmosis was exceeded by 

 the force which drives water through the skin in the opposite 

 direction to osmotic pressure. 



3. The behavior of gloves of frog's skin filled with a Ringer's 

 solution containing 6 grams of NaCl to 1000 cc. of H.,0, 

 when suspended in a Ringer's solution containing 7 grams 

 of NaCl to 1000 cc. of H 2 



Controls: The behavior of skin gloves filled wiih a Ringer's 

 solution containing 7 grams of NaCl to 1000 cc. of H 2 0, when 

 suspended in the same solution. 



This set of experiments clearly illustrates the effects of 

 the driving force of osmosis when this force is sufficiently 

 great to overcome that force by which water is driven through 

 the skin into the glove in opposition to osmotic pressure. 

 In each of the four experiments graphically represented in 

 figure 13, the skin glove containing a hypotonic Ringer's solu- 

 tion at first lost weight when suspended in hypertonic 

 Ringer (experiments 504, 505, 512, and 513). In three in- 

 stances, however, after an equilibrium had been established, 

 the gloves began to gain weight and continued to do so until 

 the termination of the experiment (experiments 505, 512, and 

 513). In this latter respect their behavior resembled that 

 of their controls (505 A, 512 A, and 513 A) which, from 

 the beginning of their suspension, gained weight continu- 

 ously under conditions in which both surfaces of the skin 

 were bathed by solutions having the same osmotic pressure. 

 In the control 513 A the glove lost weight during the first 

 hour of its suspension in Ringer; its weight then remained 

 practically stationary for about six hours, after which time, 

 however, there came a gain in weight. This form of behavior 

 has already been demonstrated for certain skins in which the 

 capacity to transport water through the skin in a Direction 

 opposite to that of osmotic pressure has been either greatly 



