254 



M. L. BASKERVILL. 



control of Ringer's solution; and less penetration than into the 

 controls in solutions containing dextrose with sufficient amounts 

 of Ringer's to protect the skin against too rapid death. The 

 skins were in the "normal" direction; washed for one hour and 

 forty-five minutes; penetration five hours. 



In order to compare the penetration of urea through dead 

 frog skin with that through living skin, the skins were killed in 

 several ways: by exposing to 60 per cent, ethyl alcohol; to 5 

 per cent, formalin; or to 0.5 per cent, sodium fluoride, from 

 forty-five minutes to one hour. Often skin that had been 

 killed in alcohol or sodium fluoride showed the passage of more 

 urea into the pure sugar solution than into Ringer's solution. 

 The reason for this behavior is not known, unless it is that the 

 constituents of the skin are not "fixed" so thoroughly by these 

 chemicals as by formalin, and therefore the subsequent treatment 

 with sugar causes more disorganization in the skin and more 

 penetration than could occur in the latter case. This point is of 

 chief interest in showing that the more viscous sugar solutions 

 do not slow the rate of diffusion of urea more than does the 

 Ringer's solution. 



In Tables IX. to XII. are presented data typical of results 

 obtained in a large number of experiments with dead skins. 

 The skins were washed in the sugar or Ringer's solution re- 

 spectively before and again after being killed in the solutions 

 indicated. Penetration of the urea continued from three to 

 three and a half hours. 



TABLE IX. 



3/19/26. 



