This is a request for a Grant to study the composition and physical properties of the peptides obtained by solubilizing collagens from modern and fossil teeth and bones of various ages. The homogeneity of the peptides and their molecular weights depend on both the age of the collagen and on the method of gelatinization. We propose to separate and analyze these peptides by techniques of gel filtration and electrophoresis and by gas and liquid column chromatography and to relate the results to the age of the protein from which they have come. In the case of the fossil collagens this is a preliminary to a sequential analysis of their molecules aimed at indicating any evolutionary changes that may have occurred.