The Morphology of Ruppia Maritinia. 123 



these land haloph}-tes, since they hve and flourish entirely in a salt- 

 water medium. 



Wishing- to ascertain how great a concentration of salt water 

 Ruppia would stand without plasmotyzing, 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 wa}*, produced a marked 

 plasmol3^sis 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 plasmoh'sis index in 

 Elodea and CaUitriche 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 (1903, 

 pp. 359, 360, 364) expressl}- states that these grow in the higher 

 and drier places of the salt marsh. 



Another point illustrated by the experiments with Elodea and 

 CaUitriche 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 naturall}' 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 ver}' delicate plant, is more sensitive 

 in both cases than CaUitriche. 



Being curious to know how much pure salt (sodium chloride) 

 Ruppia would stand, I used solutions of 2.5, 3, and 5 per cent with 

 the following results. 



1. Leaves of R. maritima. placed in 2.5 °/o NaCl solution, did not plasmolyze. 



2. „ ,, ,, ,, ,, ,, 3 "/o „ ,, plasmolyzed in 4— 5 min. 



3. ,, „ „ „ „ ,, 5 "/o „ „ „ in about 1 „ 



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. Acad.. Vol. XIV. 9 Decb:mber. 1908. 



i 



