Experiments on Absorption of Salt-Marsh Plants. 125 
were removed and replaced by fresh plants. The strength of the 
solution was found at the beginning of the experiment, after the 
removal of the first set of plants and after the removal of the second. 
The solutions were diluted and titrated with a decinormal solution 
of silver nitrate. The following were the concentrations found:— 
Strength of NaCl 
solution. 
At beginning of experiment ... ... ... 3*03% 
After immersion of first lot of plants ... ... 3*12% 
„ ,, „ second „ . 3-24% 
It will be seen from the above figures that the solution had 
increased in strength after the immersion of the first group of 
plants and had increased still further after the immersion of the 
second. The above figures are the result of a single experiment, 
and, since they as yet lack corroboration, too much stress should not 
be laid upon the actual increase of concentration. They suffice, 
however, to show that a certain amount of water had been removed 
from the solution by the plants, as care was taken that none should 
be lost by evaporation. 
(iii.) By Estimating the Difference in Weight in Individual 
Plants after Immersion. 
Plants were immersed in distilled water or in a 3% solution of 
sodium chloride and were weighed before and after immersion. 
The increase in weight found was always regarded as due to water 
absorbed, though there was the possibility that it might, in the case 
of immersion in salt solution, be in part due to sodium chloride 
diosmosing into the cells. This possibility was rejected because of 
the increase in concentration found in the experiment described 
above. 
Method. In all experiments, except the preliminary ones, the 
plants were removed from the soil and their roots, with the small 
amount of soil adhering to them, were wrapped up in several layers 
of tin-foil. The succulent parts of the plants were then put into water 
or salt solution, taken out at once and dried as thoroughly as possible 
with filter paper. They were then weighed and this weight was 
taken as the first weight of the plant, so that if there should be any 
error due to imperfect drying it should be as much as possible 
nullified. The plants were then immersed in the liquids for varying 
periods of time, then dried as before and reweighed. During 
