During the past three or four decades a tremendous amount of information has been acquired regarding the carcinogenic process. Up to the present time, search for a single cause of cancer has been fruitless. The great majority of modern cancer investigators will agree that the cause of cancer, unlike that of the communicable diseases, is complex and multiple. Cancer can now be induced at will in experimental animals by (a) more than 200 different chemicals, some of which are organ specific and induce the process in one organ or tissue only; (b) many of the energy agents (x-rays, ultraviolet light, gamma rays, etc.), especially when the tissues are subjected to interval exposures; (c) hormonal disturbances and imbalances; (d) genetic manipulations (inbreeding and cross-breeding); (e) a combination of one or more of the above factors. Recently, Copeland and Salmon1 of the Alabama Polytechnic Institute have reported the induction of cancer in rats by means of a simple dietary (choline) deficiency. While much ...