In the past, studies on the pathogenesis of retinitis pigmentosa have been concerned mainly with efforts to discover the remote causes of the disease : the influence of heredity and of consanguinity between the parents, the possible disturbance of liver function, the possible relation of vitamin deficiency, the relation of the ocular disturbance to associated conditions in other organs such as deafness, endocrine disturbances, mental defect, epilepsy, etc. The aim of the present investigation is much more modest, and is concerned with an attempt to unravel the local manifestations of the disease, and to discover what aspect of the local lesion may be considered primary and what aspects may be considered secondary to this primary lesion. For example, the disease process manifests itself in the death and destruction of the retinal neuro-epithelium, and of the retinal ganglion cells. One of the questions that we wish to