The organic compound cholesterol has long obtruded itself on the attention of those who are interested in the medical sciences. Thus, it has been recognized as a probable constituent of all animal cells—a fact which of itself contributes to the substance the dignity of a presumably essential component of living matter. The nervous system is replete with cholesterol, so that the biochemical student is accustomed to prepare it in abundance from brain tissue as a familiar laboratory exercise. What the possible significance of this unique concentration of the lipoid in the nervous system may be remains obscure, though long challenging attention. Cholesterol occurs in the bile, where its presence occasionally leads to the development of gallstones and thus excites the interest and curiosity of the surgeon and the pathologist. The genesis of cholesterol and calculi remains today as a topic that is still debated.
The circulating blood contains cholesterol esters