Experiments on Absorption of Salt-Marsh Plants. 127 
for the plants had been placed in the bottles with the soil attached 
to their roots undisturbed. In all the other experiments this was 
not the case, for, as stated above, the roots were removed from the 
soil and wrapped round with tin-foil, so that no root absorption 
could take place. These experiments are best divided into two 
groups, the first containing those that were immersed for a long 
period (17 to 24 hours), the second those that were immersed for a 
shorter period of a few hours. The experiments in which immersion 
extended over a long time were made to find out the capacity of the 
plant for absorption ; those in which immersion was for a short 
period to see what was the amount of absorption that could take 
place in such a time as the plants might be wet with rain, etc. or 
covered by the lower tides. 
For comparison of the results it was necessary to fix on some 
factor that was comparable for all plants. The percentage of 
water present in the succulent parts of the plants was found 
to vary so that the weight of the succulent part and its dry 
weight were both rejected as units of comparison, and the 
weight of the water present in the succulent part at the time of 
immersion was selected. Whenever possible, therefore, the difference 
in weight found has been calculated as a percentage of the water 
present at the time of immersion. In those cases where the dry 
weight was not found, the difference was calculated as a percentage 
of the weight of the succulent part of the plant. 
I. Effect of Immersion of Plants in Liquids for a 
Long Period. 
The plants were immersed and left overnight in distilled water 
or in a 3% solution of sodium chloride. They were weighed at the 
end of the period and a considerable increase in weight was found. 
The amount of the increase varied in different plants and there 
seems to be no relationship between the amount absorbed and the 
weight of the water or the percentage of water in the plant. In 
some cases the dry weight of the plant was not found, so that the 
increase in weight has been calculated as a percentage of the 
weight of the succulent part of the plant at the beginning of the 
experiment. Table III. gives the figures obtained. 
