THE STRUCTURE of the vitreous body is an old problem which has stimulated the attention of anatomists and ophthalmologists from the earliest time. In spite of the large amount of research work done on the subject, our knowledge of the vitreous structure is still limited. Principally, two methods of investigation have been used so far: the microscopic study of fixed material and the ultramicroscopic examination of fresh vitreous. Histological research has encountered appreciable difficulties because of the unusual delicacy of the vitreous and its high water content. Sections of fixed vitreous prepared by ordinary histological methods show the presence of a network of poorly stained, thin fibers. 1 The view has been expressed that these fibers do not represent the true vitreous structure but are merely artifacts produced by the action of fixatives on the vitreous body. Differences in the shape, size, and pattern of the fibrous elements resulting from