Judging from the extensive literature which has accumulated on cholesterol during the past ten years, this lipoid has been the subject of more varied and extended investigations than any other substance of physiologic importance. Although it has received the attention of organic and physiologic chemists and clinical investigators alike, its exact constitution and much concerning its rôle in normal and abnormal metabolism remains to be solved. It is known, however, that cholesterol is a monatomic, simple, unsaturated, secondary alcohol. It further possesses the character of a complicated terpene, which gives it a unique position in the animal organism, since no other substance has been found to have so complicated a carbon nucleus except cholic acid, which alone is analogous.
The importance of cholesterol is indicated by its widespread occurrence in the animal body. Cholesterol is obviously, therefore, a constituent of our various animal foods, from which probably much of the