Paper chromatography shows the presence of 14 amino acids in appreciable quantities, plus traces of one or two more. Most abundant are aspartic acid and alanine; next come serine, glutamic acid, glycine, and tyrosine, in approximately equal amounts. Lysine and arginine are found in equivalent, but smaller, amounts, followed by threonine and valine. Proline, hydroxyproline, leucines, and histidine occur in substantial amounts, together with traces of cystine and/or cysteine. The nitrogen content of the shell averages 13 percent, which indicates a protein content of 80 to 82 percent.