A previous contribution1 on the routes of absorption in the presence of hydronephrosis, based on experiments with molecular dyes and colloidal preparations, demonstrated that there are two routes of absorption, lymphatic and tubular. In the previous investigation, at the onset of complete ureteral obstruction there ensued for about two or three days a purely lymphatic absorption from the walls of the renal pelvis and the ureter. After approximately the third day a tubular absorption began, and this continued more actively than the lymphatic absorption. It was noted that the distal convoluted tubules of the peripheral layer of glomeruli were the first to assume this function, and as pressure atrophy progressed the subjacent tubule layers, seriatim, continued the process. The cells of the convoluted tubules by thus absorbing the mediums demonstrated a slightly altered function and one of definite significance in renal pathology. Throughout the investigation care was taken not