The etiology of the primary glaucomas is still very largely a matter of speculation in spite of the large volume of research work which has been done over the last hundred years. It is true that we now have a better understanding of the mechanics of the disease and are able to distinguish the two broad groups of closed angle glaucoma and simple glaucoma, but the underlying pathology of simple glaucoma is still unproved. It is usually assumed that simple glaucoma is a degenerative condition akin to such diseases as arteriosclerosis of the vascular system, and the usual age of onset would support such a view. It is possible, however, that other factors may be present in some cases and an investigation of persons developing the disease in the younger age groups—i.e., before the age of 50—might indicate some of these other factors and show that all cases of simple