VITAMIN A 251 



factor dc novo in animals ; but both land and water plants synthesize the 

 vitamin (at least in its precursor form) and from them the animals 

 of the land and sea, including the fishes, derive their supplies — either 

 directly or by preying upon other species. 



Coward and Drummond (1921) attempted to trace the origin of 

 vitamin A in plants by feeding tests with seeds, germinated seeds, 

 etiolated seedlings, green seedlings and older green plants for the rela- 

 tive content of vitamin A. No increase in the amount of vitamin A in 

 the barely germinated seeds could be detected. Their experiments also 

 indicated that the content of vitamin A was not appreciably greater in 

 the etiolated seedlings than in the original seeds. Green shoots of turnip, 

 maize, and peas (soil and sand grown) were, however, decidedly richer 

 in vitamin A than the original seeds or etiolated seedlings. A more 

 detailed study with the sunflower confirmed these results. The dry seeds 

 and etiolated shoots were relatively inactive, while the green shoots 

 were very active as a source of vitamin A, thus suggesting that the 

 formation of large amounts of vitamin A in green leaves requires the 

 influence of light. 



Evidence was also furnished in this contribution that vitamin A can 

 be produced by the green plant from inorganic sources as shown by its 

 high content in the green shoots of Tradescantia (Wandering Jew) 

 grown in water; that green cabbage is much richer in vitamin A than 

 white cabbage, that mushrooms contain only a small amount of vitamin 

 A, and that common green seaweeds (Ulva and Cladophora) are as 

 potent in vitamin A as the green land plants such as cabbage, and are 

 much richer in this vitamin than are red seaweed {P olysiphonia) and 

 Carrageen moss (Chondrus crispus). 



Jameson, Drummond and Coward (1922) reported the work begun 

 by the late Dr. Jameson upon the project of developing the complete 

 cycle of transfer of vitamin from the minute diatomaceous seaweeds 

 through the Crustacea and smaller fish to the cod. In the diatomaceous 

 and other green seaweeds they found evidence of formation of vitamin 

 A which they correlated with the presence of chlorophyll or related 

 coloring matter. Later Coward (1925) extended this work to the study 

 of a fresh water alga which she found to synthesize vitamin A when 

 grown in pure cultures. As little as 0.003 gram per day of the dry 

 weight of this alga proved effective as a source of vitamin A in her 

 work. 



There is no reason to doubt that the green plants of the water as 

 well as those of the land, synthesize this vitamin under the influence 

 of sunlight. Many of these diatoms, minute algae, and other tiny aquatic 



