Studies of photo-synthesis in marine algæ.—1. Fixation of carbon and nitrogen from inorganic sources in sea water. 2. Increase of alkalinity of sea water as a measure of photo-synthesis

The series of experiments recorded in this communication were carried out at Port Erin; the subsequent analyses for amounts of nitrogen fixed were made at the temporary laboratory of the Department of Applied Physiology, M. R. C., at the Lister Institute. The results of the series confirm and amplify those obtained with fresh-water algæ, which showed a convincing uptake of nitrogen from the air, but on account of the change of the medium of growth from fresh to sea water, there are several important modifications in the medium itself as well as in the growing algæ, which appear to us to possess considerable importance in the annual life of the sea, and in the inductance at certain definite periods of the year of increased processes of cell-division and reproduction of species, and possibly in guiding the development of variations in species, and the process of evolution. The details of seasonal variation in growth resulting from intensity of illumination will be given in a subsequent paper; here will be considered the changes in the algæ and the sea water due to the action of light apart from seasonal variations.