Proteolysis of the vitreous humor is directly associated with its liquefaction and degeneration. The proteolysis takes place in two ways : first, by autolysis, which may be defined as autodigestion or hydrolysis of the vitreous humor by the proteolytic enzymes which are contained in it, and, second, by heterolysis, which may be defined as hydrolysis of the vitreous humor by the proteolytic enzymes which are brought into it. In heterolysis, the proteolytic enzymes arise chiefly from disintegration of the white blood cells,1which may enter the vitreous humor by migration or in the exudates of blood serum. The thermolabile inhibitor for proteolytic enzymes, which is contained in the blood serum, is a factor in heterolysis of the vitreous portein. This inhibitor is easily overcome by abundant white cells, particularly such as occur in suppurative exudates. It tends to disappear after the serum leaves the blood vessels.1 Although attempts