Studies in Permeability. 
H. The Effect of Temperature on the Permeability of Plant 
Cells to the Hydrogen ^on. 
BY 
WALTER STILES 
AND 
INGVAR J 0 RGENSEN. 
With four Diagrams in the Text. 
I N the first of these papers we have indicated that the cells of potato 
tuber absorb hydrogen ions very rapidly, and in the succeeding article 
of this series it will be shown that this rapid absorption is a general charac¬ 
teristic of acids. It becomes of interest to discover whether this absorption 
is due to simple diffusion into the cell, whether it is due to adsorption, 
or whether the entrance of the acid is the result of its chemical combina¬ 
tion with some substance or substances of the cell, for all information of 
this kind is likely to be of help in the elucidation of the mechanism of 
permeability. We have therefore examined the influence of temperature 
on the absorption of hydrochloric acid by potato cells, as these three 
processes, diffusion, adsorption, and chemical action, should all be influenced 
differently by alterations in temperature. 
Method. 
The method of investigation has been briefly indicated in a previous 
paper, here we may give further details. 
The tissue used consisted of discs of potato tuber which were i cm. in 
diameter and weighed about 0-5 grm. They were/washed in a gentle 
stream of tap water for about an hour, then rinsed in distilled water, and 
transferred to the acid solution. 
The acid used was hydrochloric acid, made up by means of specific 
N 
gravity tables to a strength of about ^ which was diluted for use to 
o-coi N. Subsequent titration with standard alkali showed that the stock 
[Annals of Botany, Vol. XXIX. No. CXVI. October, 1915.] 
