204 
Walter Stiles 
and that it may even be complicated in structure. On this account 
it is to be regarded as quite possible that under different conditions 
of stretching or with variations of other conditions, the amount of 
water held by the cell wall may vary. That cell walls might vary as 
regards the amount of water contained in them appears to have been 
fully recognised by Pfeffer (1903). 
Some experiments of Hansteen (1914) appear particularly sugges¬ 
tive in this connexion. Pith from the leaf stalks of turnips was 
crushed in a porcelain mortar with water, and after standing for 
several hours, the solid material was washed repeatedly with water 
and then re-crushed until no intact cells remained. In this way 
material was prepared which was regarded as consisting entirely of 
cell wall. A weighed quantity of this product was dispersed in a very 
fine condition through cold tap water and allowed to settle on filter 
paper placed on a sieve. The paper was then removed and dried 
under pressure in a press. In this way membranes were obtained 
90 to 100/x thick, and used with an area of 3 x 1 cms. Experiments 
were conducted on the water uptake of these membranes and their 
behaviour in this respect compared with that of similar membranes 
from which lipoid substances had been removed by treatment with 
hot alcoholic hydrochloric acid, and also with membranes of parch¬ 
ment paper. 
Such membranes were immersed for definite times in solutions 
of various salts, and the water absorbed measured by the gain in 
weight. Measurements were also made of the rate of water loss by 
evaporation from the membranes after removal from the solutions. 
In Table XXV are shown some of the results obtained by Hansteen- 
Cranner with regard to the uptake of water by his artificial cell 
membranes when immersed in various solutions at 15*5° C., 10 c.c. of 
liquid being used in each case. 
Table XXV 
Uptake of water by artificial cell-wall membranes in different 
solutions. (Data from Hansteen-Cranner) 
Solution 
Concentration 
in gram-mols. 
per litre 
Uptake of water in per¬ 
centage of original 
weight of membrane 
Loss of water from soaked 
membrane by evaporation 
in air at i8° C. for io mins. 
CaCl 2 
O-I M 
152-27 
77-61 
KC1 
01 M 
205-19 
44-77 
NaCl 
o-i M 
222-00 
54*05 
Water 
— 
175-00 
62-50 
CaCl 2 
o-oi M 
I 75-82 
73-75 
KC1 
o-oi M 
294-87 
59-13 
NaCl 
o-oi M 
333-34 
62-73 
Water 
— 
172-41 
6i-oo 
