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vital processes of plants which are generally supposed to be very 
sensitive to changes in the osmotic pressure of the surrounding 
medium. A conclusion based on the following observations: — 
1. Delicate marine Algae taken from the sea and placed in 
fresh water grew for months. 
2. Plants transferred from ordinary sea-water directly to 
saturated sea-water, flourished for one or two months. 
3. Algae taken from the sea lived for relatively long periods in 
sea-water to which had been added three or four volumes of 
distilled water. 
It is clear that these observations are of the same nature as 
those considered in the present communication ; and it does not 
appear unreasonable to presume that the marine Algae have the 
same power of rapidly adjusting their internal osmotic strength, 
according to the salinity of their surroundings, in the same way as 
salt-marsh plants. In other words, osmosis is a far more delicate 
mechanism, in the living organism, than Osterhout’s conclusion 
would lead us to suppose, and this is probably the explanation of 
the above facts observed by Osterhout. 
Drabble and Lake 1 also have published valuable results which 
bear upon the present observations. They have found that “ a 
greater concentration of cell-sap occurred in those plants which 
had been most strongly subjected to factors tending to promote 
loss of water by transpiration.” Thus Taraxicum Dens-leonis 
growing in damp long grass near a water-course showed a low 
osmotic equivalent, while Vactinium myrtillus growing on rocks 
was shown to have a comparatively high osmotic strength. 
Further, Geranium Robertianum, growing near a salt marsh, had 
a slightly lower internal osmotic strength as compared with 
another individual of the same species, growing on rocks at some 
altitude. In a later publication 2 these same authors have shown 
that:— 
1. The osmotic strength is least in submerged fresh-water 
plants and greatest in salt-marsh plants. 
2. The greater the physiological drought under which the 
plants are accustomed to grow, the greater the osmotic strength 
of the sap of the turgid cell. 
1 Drabble and Lake. The osmotic strength of cell-sap in plants 
growing under different conditions. New Phytol., IV., 1905. 
2 The relation between the osmotic strength of cell-sap in 
plants and their physical environment. Bio-Chem. Journal 
II., 1907. 
