We have recently proposed the group designation of "mucolipid"1 for the complex lipid polymers that combine characteristics of the cerebrosides with others usually assigned to the mucoids. This term, which has since enjoyed wide adoption, favors concomitant recognition of the existence of a varied family of related but unique substances, soluble in both water and organic solvents, and having, as constituents, fatty acid, sphingosine or a similar base, hexose, and also N-acetyl hexosamine, often amino acids and, most significantly, sialic acid or a related substance. Lipids of this type were encountered 23 years ago by Landsteiner and Levene2; in succeeding years, they have been uncovered in spleen,3 normal brain,4 Niemann-Pick brain5 and, in dramatic superabundance in human brain tissue in advanced stages of infantile amaurotic idiocy (Tay-Sachs' disease).
Our original investigations on the mucolipids of brain were prompted by several unique observations. It was found that a preparation obtained by