Edited by

The Carnegie Institution's project on the mass culture of algae is a collateral development or offshoot of its program of research on photo-synthesis. One part of this program was concerned with the nature of the products which the plant makes in the photosynthetic process [200]. Several widely different species of plants were used in these investiga-tions, but particular attention was paid to the unicellular alga Chlorella pyrenoidosa [201], because of the broad range of environmental condi-tions under which it can grow, and because this organism has been ex-tensively used as a subject of study of many other aspects of the photo-synthetic problem. The experience gained in the culture of Chloreila was applied to a wartime investigation, namely, the search for an antibacterial substance that might be isolated from the culture solution in which Chlorella was grown [202]. It turned out that the antibiotic activity resulted from a complex photooxidation of the unsaturated fatty acids in the Chlorell