THE PERMEABILITY OF FROG SKIN TO UREA. 



TABLE II. 



243 



Date of experiment 11/3/22. 



TABLE III. 



Date of experiment 11/11/22. 



Isotonic CaCls and XaCl. 



Isotonic NaCl. 



Table IV. is another typical series with the skins "turned" 

 over 1 6 mm. tubes. The skins were washed for one hour in the 

 respective salt solutions and then immersed in 5 per cent, urea 

 dissolved in w r ater. Penetration continued for three hours and 

 twenty minutes. 



TABLE IV. 



Date of experiment 12/12/22. 



