246 
Walter Stiles 
Dissolved Substances 
The investigation of the influence of dissolved substances on the 
intake and exosmosis of water by plant tissue (potato tuber and 
carrot root) has also been investigated by Stiles and Jorgensen 
(1917 b) using the change in weight method. Some further observa¬ 
tions have been made by Thoday (1918 a) using the same method in 
a cruder form. As the results obtained show that the influence of all 
dissolved substances is not the same, it will be convenient to consider 
the different cases separately. 
Fig. 9. Curves illustrating the absorption of water by potato tuber immersed 
in distilled water and sucrose of various concentrations (0*2 M to 0-4 M ). 
(After Stiles and Jorgensen.) 
i. Sucrose 
Experiments were conducted on potato tissue at 20° C. with the 
same technique as that already described. Sucrose solutions of 
various concentrations were employed, the absorption-time curves 
for the tissue in the different concentrations of sucrose being shown 
in Fig. 9. It will be observed that with increasing concentration of 
sucrose both the rate of water intake and the total amount of water 
absorbed are reduced, and that in a solution of about M//[ concentra¬ 
tion the intake of water is approximately zero. With higher con¬ 
centrations of the sugar exosmosis of water takes place, both the 
