10 CHARLES F. W. McCLURE 



It has often been stated that the skin of frogs of the same 

 as well as of different species may vary greatly in its general 

 character, especially as regards permeability. Since we now 

 recognize the fact that water is transported through the skin 

 into the glove when the latter, with the outside of the skin 

 turned outward, is filled with a Ringer's solution and is sus- 

 pended in the same solution, it seems probable that a study 

 of frog skins, as regards their relative permeability, might 

 throw a new light on still other phenomena associated with 

 the transport of fluid through the skin. 



The technique employed in the preparation of the skin 

 gloves used in this investigation was essentially the same as 

 that employed by other investigators. In most cases the 

 skin of the hind legs was used in the form of a glove, a liga- 

 ture being applied to the opening left where the skin had 

 been cut off at the ankle. The upper end of the glove was 

 tied to a glass tube, which was then closed by a paraffined 

 cork to prevent evaporation of fluid placed in the glove when 

 the latter was suspended in solutions. This method of prepa- 

 ration allows the experimenter to change the fluid in the 

 glove, and so to make use of the same glove for different 

 experiments. At stated intervals the gloves were removed 

 from the solutions and were weighed. Always the outside of 

 the skin was dried rapidly with filter-paper before the weigh- 

 ing was done. The experimental error involved in weighing 

 skin gloves obtained from the hind legs of small frogs 

 amounted to about 5 milligrams. 



II. THE BEHAVIOR OF GLOVES OF FROG'S SKIN, WITH THE 

 OUTSIDE OF THE SKIN TURNED OUTWARD, WHEN FILLED WITH 

 RINGER'S SOLUTION APPROXIMATELY ISOTONIC WITH FROG'S 

 BLOOD, AND SUSPENDED IN THE SAME SOLUTION 



The writer has made a large number of these experiments. 

 They were made in every month of the year; the skins used 

 were taken from living frogs which had been recently cap- 

 tured, and also from frogs which remained in captivity with- 

 out food for several months prior to the experiments. The 

 normal average behavior of the skin gloves has been graphi- 



