Osmotic Properties of Salt Marsh Plants. 137 
solution in immediate use. As this occurred frequently, fresh 
seedlings of Salicovnia were removed from the earth and examined 
in a molecular solution of common salt; if the root-hairs resisted 
this concentration, and showed no plasmolysis, the plants were 
placed in fresh, or very slightly saline water, for varying periods of 
time, at the conclusion of which the osmotic equivalent of the root- 
hairs was determined. 
TABLE IV. 
Locality. 
Period of Soaking. 
Osmotic Equivalent. 
S—-4 
5 hours ... 
2-4% NaCl 
S—-4 
12 
• •• L ±4 yj ••• 
1-91% „ 
Tansley’s Pan ... 
... 18 „ 
3-31% „ 
These results (Table IV.) indicate that the osmotic strength of 
the cell-sap of the root-hairs varies with the concentration of the 
surrounding medium, being lower when the external solution is 
weaker and, on the other hand, is greater when the concentration of 
the surrounding solution is higher: a result which is in agreement 
with those obtained by Mayenburg 1 and others for fungus hyphae. 
This being so, it appeared unnecessary to determine the exact 
osmotic equivalent, and in the following experiments this was not 
done in all cases. The root-hairs of fresh Salicornia seedlings were 
tested to see whether they could resist a 5'8% solution of common 
salt; all so proved could, and they were then soaked in a 1% solution 
of sodium chloride for two hours, after which treatment they were 
found to be plasmolysed in the original 5-8 % solution of salt. 
Similar experiments were performed by allowing the sod, 
containing the seedlings in situ, to soak for eighteen hours in stream- 
water, and testing a few seedlings from it before and after the 
soaking. Previous to immersion in the fresh water, the root-hairs 
resisted the molecular solution of salt, but after the washing-out 
they were readily and much plasmolysed by a solution of the same 
strength ; subsequently, the internal osmotic pressure was found to 
be equivalent to a 3'31% solution of chloride of sodium. 
These results, obtained in the spring of 1907, clearly show 
that the root-hairs of Salicoynia, growing in places where the soil- 
water is strongly saline, can accommodate their internal osmotic 
pressure as the salinity of the water of the surrounding medium 
falls in concentration. 
1 Prings. Jahrb. f. Wiss. I3ot., 36, 1901. 
