“…With the exception of the titratable sulfhydryl groups, the analytical composition of the homologous liver nucleoproteins was found to be independent of the species studied (169). The myosins (38) and the brain proteins (65,66) of several species appear to possess, like the liver nucleoproteins, an amino acid composition which is very nearly the same for all the species studied. These observations on homologous proteins are of considerable comparative biochemical interest.…”