“Analogies between the phosphorized fats obtained from the brain and kidney,” with exhibition of products

So much attention has been directed to the protein constituents of protoplasm that it has become usual to regard proteins as the physical basis of life. Relatively recent investigations have, however, indicated that all cells contain complex substances of a fatty or lipoid nature, in which phosphorus and nitrogen are conspicuous elements. Many of these lipoids possess remarkable physical properties. In contact with water or alkaline liquids, they pass into colloidal solution after imbibing large quantities of water with the production of “myelin forms.” They also differ from neutral fats in doubly refracting light. Such physical characters and the complex molecular constitution of these lipoids appear to justify the assumption that they, as well as proteins, are essential constituents of protoplasm and that a study of living matter must include the consideration of these compounds of the fatty acids.

The phosphorized fats, or lipoids, which have been most carefully studied have been obtained from the brain, 1 but even as derived from this source, where they are believed to be present in relatively large amounts, their constitution and mutual relationships have not been clearly established.

During investigations of alcoholic extracts of kidneys, the writer has been led to infer that substances closely related to the lipoids derived from the brain may be obtained by similar methods from the kidney, and the purpose of the present communication is to report a few representative analyses from among those upon which the inference just stated is based.

Extracts of finely divided renal tissue, freed from obvious fat, made with hot 85 per cent. alcohol, yield a precipitate, upon cooling, which contains a variety of lipoids, while certain others remain in solution. For convenience, those lipoids which are relatively insoluble in cold alcohol may be classed as the “protagon” group, and those not precipitated on chilling as the “lecithin” group.