THE HISTOGENESIS OF CHRONIC URANIUM NEPHRITIS WITH ESPECIAL REFERENCE TO EPITHELIAL REGENERATION.

1. Proliferation of connective tissue in chronic uranium nephritis is early and progressive and due to a direct stimulation on the part of the uranium. 2. The hydronephrotic theory fails to explain the phenomena observed in the progress of the chronic nephritis. 3. Carmine is deposited, as shown by Suzuki, in the proximal convoluted tubule only, and in different amounts in different levels of this segment of the tubule, so that subdivisions may be made. 4. Regeneration begins about the fourth day, but varies in proportion to the dose of renal irritant given. 5. The first cells to appear are large vesicular elements, and there is a gradual development of syncytium-like masses and giant-cells. These last are due to the rapidity of cell division. 6. Small, deeply staining nuclei, which are morphologically identical with the newly regenerated cells described by Thorel and others, are present from the first day of the acute nephritis and are persisting renal cells which have been slightly affected by the toxic agent.