THE PERMEABILITY OF FROG SKIN TO UREA. 



2.SI 



In Tables II. and III. are presented typical data showing the 

 penetration of urea dissolved in varying concentrations of 

 dextrose. The Ringer's and dextrose solutions were in contact 

 with the inner surfaces. The percentage of isotonic sugar 

 solution is indicated in the first column; it is made up to 100 cc. 

 with Ringer's solution in each case. The skins were washed for 

 one hour in the respective solutions. Penetration was allowed 

 to continue for three hours. The skins were "turned." 



TABLE II. 



11/30/25. 



Isotonic Dextrose + Ringer's Solution. 

 Per Cent. 

 Dextrose. Mg. Urea. 



SO ... 7.32 



75- 5-i6 



85 5-22 



90 7-50 



95 1.68 



100 0.96 



TABLE III. 



12/1/25. 



Isotonic Dextrose + Ringer's Solution. 



Per Cent. 



Dextrose. Mg. Urea. 



50 3-72 



75 ... 2.76 



85 4-o8 



90 4.80 



95- 2.64 



zoo. . i. 20 



Ringer's Solution. 



Mg. Urea. 

 7.86 

 7-44 

 8-34 

 7.86 

 9.48 

 8.04 



Ringer's Solution. 



Mg. Urea. 

 5-88 



7-74 

 6.66 

 7.02 

 8.70 

 4-74 



Results with the skins in the reverse relation are given in 

 Tables IV. and V. The skins had the inner surface in contact 

 with the Ringer's or sugar solutions, and the outer side in contact 

 with five per cent. urea. The skins were washed for one hour 

 in the respective solutions. Penetration continued for three 

 hours, and the skins were in the "normal" direction. 



The results with sucrose differed no more from those obtained 

 with dextrose than did results with either sugar alone when 

 different skins were employed, as is indicated by the data 



