On the Effect of Nitrates on the Carbon- 
Assimilation of Marine Algae. 
BY 
E. A. NEWELL ARBER, B.A., 
Trinity College , Cambridge ; University Demonstrator in Palaeobotany. 
I N a former paper \ some account was given of experiments 
on the effect of salts on the assimilation of carbon dioxide 
in Ulva latissima , L. The object of that work was to obtain 
some qualitative idea of the relative value of the principal 
salts of sea water in regard to the maintenance of carbon- 
assimilation. The salts, then made use of, were the chlorides 
and sulphates occurring in sea water. In the present com- 
munication will be found an account of experiments with 
nitrates, and other salts, on the same Alga by a similar 
method, and of attempts to extend the work to other marine 
Chlorophyceae. 
Nitrates. 
* 
Molisch 2 and Kossowitsch 3 have shown that the higher 
Algae obtain their nitrogen entirely in the combined form. 
Very little is known of the influence of nitrates on marine 
Algae. With fresh-water Algae, the effect of the presence of 
different nitrogenous compounds in the medium seems to vary 
1 Arber (’01), p. 39. 2 Molisch (’95). 
3 Kossowitsch (’94). 
[Annals of Botany, Vol. XV. No. LX. December, 1901.] 
