In the course of experiments having for their object the study of the properties of vitamin A with a view to its isolation, certain observations were made concerning the behavior of animals on various rations containing cod liver oil. It was noted that different samples of cod liver oil apparently vary markedly in vitamin A potency. Xerophthalmia has been produced in rats on diets containing as much as 3 per cent of cod liver oil. Synthetic rations containing cod liver oil evolve a penetrating odor resembling acrolein. When the cod liver oil is replaced with butter fat, this odor is not observed. It is possible that the failure of rats on diets containing certain samples of cod liver oil may be due to one or more of the following factors. 1. A decreased consumption of the diet clue to this decomposition product. 2. A destruction of vitamin A which runs parallel with the destruction of the cod liver oil. 3. Certain samples of cod liver oil are not as rich in vitamin A as supposed heretofore
