6 i 8 Stiles and Jergensen.—Studies in Permeability . II. 
membrane. We feel, however, that more experimental evidence is required 
before such theories can be discussed adequately and with profit. 
Summary. 
1. The absorption of the hydrogen ion of hydrochloric acid in dilute 
solution by potato cells takes place according to a simple exponential 
relation between time and the concentration of the acid. 
2 . The rate of absorption of these ions by potato cells is increased 
about 2*2 times for a rise of io°C. between o°C. and $o°C. 
Botany Department, 
The University, Leeds, 
June 14, 1915. 
