In a previous paper, our first communication on this subject (‘ Phil. Trans./ B, vol. 194, 1901, p. 515), we have shown that the poisonous effects produced by the young plants of Lotus arabicus are due to prussic acid, which is not present in the plant as such, but originates in the hydrolytic action of an enzyme, lotase, on a glucoside, lotusin. Recently we have examined a large number of plants which, like this Egyptian vetch, appear, under certain conditions, to possess poisonous properties, and at other times to be innocuous and often valuable as fodder plants or food stuffs, with the view of ascertaining to what extent they contain glucosides furnishing prussic acid. Among the first of these plants we examined was the Great Millet, Sorghum vulgare , a plant widely cultivated in tropical countries for the sake of its nutritious grain, which in many districts of India is the staple food, known as “Juar,” of the natives. In the West Indies what is apparently the same plant yields the important “Guinea Corn” and in South Africa “Kaffir Corn.”