34 CHARLES F. W. MCCLTJRE 



that we may account for the greater loss in weight of the 

 glove in experiment 513 on the ground that in this particular 

 skin, as in that of its control (513 A), there was acting in 

 opposition to osmotic pressure no force by which water could 

 be simultaneously driven through the skin into the glove. 



It would appear that the behavior manifested by skin 

 gloves, with the outside of the skin turned outward, when 

 filled with a hypotonic Ringer's solution and suspended in a 

 hypertonic Ringer's solution, may be the resultant of the 

 action and interaction of the following separate and distinct 

 factors: osmotic pressure; the capacity of the skin itself to 

 gain and to lose water; and a force which drives water 

 through the skin in a direction opposite to that of osmotic 

 pressure. Also, we find that skin gloves filled with a hypo- 

 tonic solution and suspended in a hypertonic solution begin to 

 gain weight after an equilibrium has been established, in pro- 

 portion to the capacity of the skin to transport water through 

 itself when both its surfaces are bathed by solutions having 

 the same osmotic pressure. 



VI. ON THE TEANSPOET OF WATEE THEOUGH THE SKIN IN THE 

 LIVING FBOG WITH UEETEES LIGATED, WHEN SUSPENDED IN A 

 HYPEETONIC SALINE SOLUTION 



It has been shown by the writer in a former paper ('19) 

 that when the ureters have been ligated and a frog or toad 

 is placed in water, there immediately follows a gain in body 

 weight which may gradually result in an intense form of 

 generalized oedema. These experiments should not be con- 

 fused with those of Overton ('04), who ligated the cloacal 

 opening, but not the ureters. When only the cloacal opening 

 is ligated, the flow of urine through the ureters into the blad- 

 der and cloaca is not interrupted. In such cases, as stated by 

 Overton, the bladder becomes filled with urine which backs 

 up into the digestive canal. After the cloacal ligature is re- 

 moved, this urine is readily expressed from the bladder and 

 intestinal canal. On the other hand, after the ligature has 

 been removed from the ureters, ordinarily no fluid can im- 

 mediately be expressed from the cloaca, as in this case the 



