250 M. L. BASKERVILL. 



other. For example, if sugar solution was in contact with the 

 inner surface of the skin, after five or six hours urea penetrated 

 much more rapidly from the outer surface than was the case if 

 the reverse relations held. For this reason, while results are 

 reported below for both directions, it is considered that the 

 more significant ones were obtained with skins that had their 

 inner surfaces in contact with urea solution, which seems fairly 

 harmless for the tissue, and the outer surface in contact with the 

 sugar solution. The use of solutions abnormal for the skins is 

 discussed in detail in the recent article by Bauer (8). 



DATA. 



Throughout the tables "normal" direction indicates that the 

 inner surface of the skin was toward the tube and hence in 

 contact with the sugar or Ringer's solution respectively, and the 

 outer surface in contact with the urea; while "turned" indicates 

 the reverse relation. The amount of urea penetrating was 

 determined by the Van Slyke-Cullen method, and is expressed 

 in milligrams in all tables. The figures for matched skins are 

 given in parallel columns. 



The data outlined in Table I. show the kind of results always 

 obtained when pure sugar solution and Ringer's solution were 

 compared with the skins turned in the two directions. The 

 skins were washed forty minutes in Ringer's or dextrose solution, 

 respectively. Penetration was allowed to continue for three 

 hours and forty minutes. 



TABLE I. 



4/2/23. 



Isotonic Dextrose Solution. Ringer's Solution. 



Skins "Normal" Direction. 



Mg. Urea. Mg. Urea. 



5.88 9.72 



4.50 9.00 



5.40 IO.2O 



Average 5.26 Average 9.84 



Skins " Turned." 



2.16 14.46 



2.46 15.60 



2.40 17-52 



Average 2.34 Average 15.86 



