For the pathological studies with single kidney, already partialy nephrectomised, were searched, and the following conclusions were obtained. 1. Healing of wound is about from 35 to 42 days after the operation. Scarline is a few milimeters brest and crealy different from the distant part. 2. Glomerular or tubular degenerations of the distant part are sever in three days after the operation, and two weeks after are not found. 3. Cortical anaemia and medullary hyperemia are most severe in the third day, and the later was searched even in the 8th week. 4. Any time the changes of glomeruls are more slightly than the changes of tubulus, and the regeneration was eminent in the later. 5. The changes in the renal clearance test were certainly parallel to the changes in the pathological study. 6. The degree of glomerular or tubular degenerations was not influenced on account of the volume which had been removed, but on accout of renal ischaemia.