Osmotic Properties of Salt Marsh Plants . 139 
under observation; all of which, in a preliminary trial, were 
strongly plasmolysed by a 3'5% solution of sodium chloride. The 
seedlings were then rinsed in dilute saline, and were brought up 
through successive concentrations to a 3-5% solution; after being 
allowed to remain in this for some time the root-hairs were again 
examined. Of the five seedlings taken, the root-hairs of four 
showed a practically complete recovery, being now not plasmolysed 
by the 3 - 5% solution of salt, which, previously, affected them strongly. 
The fifth seedling, however, showed many hairs which had not 
recovered their turgidity ; the treatment was therefore continued, 
but the result was the same. The anomalous behaviour of this 
seedling being inconsistent with the experience gained from the 
previous experiments, it was considered possible that the earlier 
treatment had been too severe, and that the seedling, or at any 
rate the root-hairs, were in an unhealthy condition. In order to 
see whether this was the case, the plant was placed for definite 
periods of time in successively weaker solutions of salt, viz. 3%, 
2-4%, l'7% and lastly fresh water. After each successive bath, the 
root-hairs were still found to retain their plasmolysed condition, 
and this, even after a prolonged treatment with fresh water. It 
was thus clear that the hairs were either dead, or were in a con¬ 
dition of so low a vitality as to preclude their recovery. Conse¬ 
quently the results given by this particular seedling may be 
rejected; in no way do they invalidate those afforded by the 
other individuals. 
The observations here recorded show that the root-hairs can 
accommodate their internal osmotic pressure in proportion to the 
osmotic strength of the soil-water. This, of course, is what we 
should expect from theoretical considerations, but, at the same 
time, the experimental results may be of interest and not without 
value in providing concrete examples of the adaptability of root- 
hairs, and in confirming conclusions based on theory. 
Attention may here be drawn to the interesting work of 
Osterhout, 1 who showed that marine Algse attached to the sides of 
steam-boats may be subjected to great ranges in the salinity of 
water, the daily change being from saturated sea-water on the one 
hand, to perfectedly fresh water on the other. He further 2 
suggests that osmotic pressure may play but a small part in the 
1 Osterhout. The resistance of certain Marine Algae to changes 
in osmotic pressure and temperature. Univ. Calif. Publica¬ 
tions, Vol. II., No. 8, 1906. 
2 The role of Osmotic Pressure in Marine Plants, Id., No. 9, 1906. 
