The Morphology of Ruppia Maritima. 123 
these land halophytes, since they live and flourish entirely in a salt- 
water medium. 
Wishing to ascertain how great a concentration of salt water 
Ruppia would stand without plasmolyzing, I tried first a 105 per cent 
solution, obtained by evaporating salt water (taken at high tide at 
Savin Rock, near the entrance to New Haven Harbor), to the 
desired concentration. As is indicated in the following table, 
(p. 125), both leaves and root hairs showed occasionally a very 
slight plasmolysis. In the root hairs, indeed, the protoplasmic move- 
ment continued, although in most cases the ends of the hairs, 
especially, showed a slight plasmolysis. A solution of 110 per cent 
strength, however, prepared in the same way, produced a marked 
plasmolysis in both leaves and root hairs. 
In order to get a comparison with submerged fresh water plants, 
I experimented with the leaves and root hairs of Elodea and Calli- 
triche, with the results as shown in the table (p. 125). 
Compared with Ganong’s results, a few of which also are given 
in the table, my experiments show that the plasmolysis index in 
Elodea and Callitriche is about equal to that of Atriplex and Hordeum, 
so that there is very little halophytic adaptation in this respect in 
the latter plants. This is to be expected, since Ganong (4903, 
pp. 359, 360, 364) expressly states that these grow in the higher 
and drier places of the salt marsh. 
Another point illustrated by the experiments with Elodea and 
Callitriche is the slightly greater resistance in both cases of leaves 
as compared with root hairs. This is hardly to be looked for, since 
it would naturally be supposed that the roots would be accustomed 
to somewhat stronger solutions in the soil and would therefore 
evince a greater resistance to the plasmolyzing action. 
Elodea, as is natural, being a very delicate plant, is more sensitive 
in both cases than Callitriche. 
Being curious to know how much pure salt (sodium chloride) 
Ruppia would stand, I used solutions of 2.5, 8, and 5 per cent with 
the following results. 
1. Leaves of R. maritima, placed in 2.5 °/) NaCl solution, did not plasmolyze. 
2 Sd 
Se ” ” 0 ” ” : 0 
i? "i ,», plasmolyzed in 4—5 min. 
5, ae ese eee * wan about. 2b ';; 
Since ocean water in general is known to contain about 3.5 per 
cent of salts (Atkinson, 1905, p. 622), it would seem from the above 
that Ruppia could not live in it. And yet, as the table (p. 125) 
shows, Ruppia does not plasmolyze in the salt water of New 
Trans. Conn. Acap., Vol. XIV. 9 Drcemper, 1908. 
