On the Effect of Salts on the Assimilation 
of Carbon Dioxide in Ulva latissima, L. 
BY 
E. A. NEWELL ARBER, B.A., 
Trinity College , Cambridge, University Demonstrator in Palaeobotany . 
Section I. Method. 
HE primary object of this research was to obtain some 
JL idea of the extent to which the power of carbon- 
assimilation is dependent on the absorption of nutrient salts, 
and of the inhibition caused by the presence or absence of 
certain salts in the medium. The experiments were intended 
to be primarily qualitative rather than quantitative, and the 
standpoint throughout was the power of carbon-assimilation, 
and not growth or development. 
For this purpose a plant possessing a minimum of specializa- 
tion in regard to both carbon-assimilation and absorption was 
best suited. Certain marine Chlorophyceae present an addi- 
tional advantage in that they grow in a medium containing 
an exceedingly constant proportion of dissolved salts. The 
Alga used throughout this work was Ulva latissima , Linn. 
Enteromorpha intestinalis , Link., was also tried, but presented 
difficulties which were for the most part absent in the case of 
Ulva , and for this reason was early abandoned. 
The method employed was to obtain Ulva free from starch, 
and then to expose it to light for various periods in solutions 
of known composition. The amount of starch formed in each 
[Annals of Botany, Vel. XV. No. LVII, March, 1901.] 
