ANALYTIC DATA concerning the naturally occurring proteins of the aqueous humor are scant, the measurements presenting two major difficulties: the small amount of available fluid and its low protein content. Duke-Elder1 separated albumin and globulin in pooled aqueous of three species of animals by fractional precipitation with neutral salts and found the albumin-globulin ratio similar to that occurring in the serum of the respective species. The specific identity of the fractions separated from the horse aqueous with serum albumin and serum globulin of this species was demonstrated by Duke-Elder1 on the basis of their antigenic properties. Kronfeld2 obtained in several instances positive precipitin reactions with human aqueous on serums of rabbits which were immunized with human serum albumin and globulin. It was assumed, therefore, that the proteins in the aqueous of normal eyes in the examined species originated mainly in the blood serum, with a possible inconspicuous