124 A. H. Graves, 
Haven Harbor, and not often even in a 105 per cent strength 
solution of this. 
This would lead one to conclude a priori that the water of New 
Haven Harbor does not contain as much salts as the 3 per cent quantity 
of NaCl of the above experiment, and certainly not as much as 
the 3.5 per cent of ordinary ocean water. 
On next ascertaining the percentage of salts contained in the 
water of New Haven Harbor (procured, as in the first experiment, 
from Savin Rock, near the entrance to the Harbor, at high tide), 
I found by evaporation that the proportion was about 2.8 per cent, 
as would be expected from the @ priori conclusion. This amount, 
therefore, explains why Ruppia plasmolyzed in a 3 per cent salt 
solution, but did not plasmolyze in the water of New Haven Harbor. 
The sea water used, although purposely obtained at the entrance 
to the harbor and at high tide, is, therefore, quite brackish. The 
fact that Long Island Sound is considerably shut off from the ocean 
and also has several large rivers emptying into it, probably 
accounts for this. Very probably a similar percentage of salts 
prevails all along the Connecticut coast. 
It is possible that the sea water used in Ganong’s experiments 
had a greater content of salt. If so, his results with Atriplex and 
Hordeum mean somewhat more than the comparison in the table 
indicates. 
An interesting point which should not be overlooked, since it 
shows how delicately adjusted these plants are, comes to light in the 
sometimes slight plasmolysis of Ruppia in the 105 per cent solution. 
A little calculation shows that this is about identical in strength with 
the 3 per cent salt solution, at which plasmolysis occurs very slowly. 
It is perfectly clear, then, that Ruppia is adapted to life in water 
containing a solution of sodium chloride and other salts; that this 
solution does not equal in strength that of the ocean in general and 
hence may be termed brackish; and furthermore, that Ruppia could 
not live in such ocean water; that this adaptation of the plant is 
brought about through an ability to resist plasmolysis by maintain- 
ing in some way a higher osmotic tension than prevails in submerged 
fresh water plants, probably by the presence of an equalizing salt 
solution in the cells themselves. 
