Those species of plants in which there is considerable information on the genetics of chlorophyll deficiency furnish favorable material for a study of physiological control by the gene over the production of chlorophyll and related pigments. This study is a preliminary survey of the pigments of a number of genetically different chlorophyll mutant stocks in barley. Rabinowitch (8) has pointed out that apart from the isolated observation of Inman and Blakeslee (d), who reported a chlorophyll with a different absorption spectrum from ordinary chlorophyll in an X-rayed mutant of Datura, the chlorophyll of all higher land plants investigated has been found to consist of the two components?the blue-green chlorophyll a and the yellow-green chlorophyll b. However, W. H. Eyster (3) in 1924 reported the common occurrence of four types of pigment-deficient plants in maize. These plants were those which: (1) contained carotin, xanthophyll and chlorophyll a but lacked chlorophyll b; (2) contained carotin, xanthophyll and chlorophyll b but lacked chlorophyll a; (3) contained carotin, xanthophyll and chlorophyll a and b in varying amounts; and (4) contained carotin and xanthophyll but lacked both chlorophyll a and chlorophyll b. Eyster reports that in his studies plants which lack either chlorophyll a or chlorophyll b are unable to synthesize sufficient carbohydrates to grow to maturity. Except for this one report by Eyster, the only organisms in which a chlorophyll component has been found lacking are some of the algae, (2), (?), (12), (13), (15), (16), (18). The descriptive term chlorina has been applied to certain pale green chlorophyll-deficient characters in barley. The color may vary from pale green to yellow green in different chlorinas. Several of those chlorophylldeficient chlorinas have been described by Robertson (10), Nilsson-Ehle (7) and others. Most of them, when studied in crosses with normal green plants, differ from the normal by one recessive gene. Robertson (9) described one chlorina, however, which is apparently maternally inherited. When this chlorina, Coast V, is used as the female parent and crossed with green, the Fi, F2 and F3 are all chlorinas. The reciprocal cross, using it as the male parent, results in normal F,, F2 and F3.