A METHOD of obtaining protein macro-molecules in crystalline form by the use of heparin has been described by Cohen1. As melanin is generally believed to have a high molecular weight, an attempt has been made to crystallize it by Cohen's method, using ethylene chlorhydrin as solvent. Heparin is not soluble to any appreciable extent in pure ethylene chlorhydrin ; but both it and melanin are soluble in a mixture of equal parts of water and ethylene chlorhydrin. 'Dopa' and Sepia melanin have been used, with concentrations of heparin of 1, 2, 5, and 10 percent, with and without addition of electrolyte (sodium chloride), at temperatures varying from 20° to 20° C. The attempt has failed completely, no precipitate being observed under any conditions even after standing for seven days.