The present study represents an attempt to establish a working hypothesis in regard to the nature of acute glaucoma. Hitherto, in the elaboration of theories of glaucoma, both acute and chronic glaucoma have been considered together. This effort at a unitary theory of glaucoma perhaps has come about because the end-results of acute and chronic glaucoma present many points of identity. It may even be possible that at some future time the same ultimate cause of both diseases will be discovered. Such an ultimate cause, however, is beyond the scope of the present study. But whatever the ultimate cause or causes of acute and chronic glaucoma, there can be little doubt that the mechanism by which an attack of acute glaucoma develops is essentially different from that which produces the clinical picture of chronic simple glaucoma. We are therefore justified in omitting the problem of chronic glaucoma from consideration