THE GLOMERULI AND TUBULES 721 



experiments, but obtained a different result. He found that it 

 was impossible to remove the whole medulla without interfering 

 with the blood supply of the cortex, and so causing its necrosis. 

 With partial excision of the medulla he observed no increased 

 secretion of urine. He found that the relation of the intake of 

 water and its output as urine was normal, and that there was no 

 change in the animal's metabolism except such as could be 

 accounted for by deficient food. 



The occurrence of diuresis following excision of one kidney 

 and a portion of the other has been confirmed by Bradford, who 

 used a different method. He excised a large wedge from a dog's 

 kidney, and after the wound had healed removed the other kidney 

 whole. He obtained one of two results according to the amount 

 of kidney substance ultimately left. If as much as one-third of 

 the total kidney weight was left, the operation was not followed 

 by death. But the urine excreted was altered in quantity and 

 composition. The daily quantity of urine passed was increased 

 twofold or more, and the animal was extremely thirsty ; the 

 urine was of low specific gravity, and the total daily excretion of 

 urea was not increased. The blood was hydrsemic and contained 

 a slightly increased percentage of urea. An increased quantity of 

 proteid food caused the total daily quantity of urea and urine to 

 rise, but the urine was of the same character as before. In fact,, 

 the animal seemed to have lost the power of excreting a con- 

 centrated urine with a high percentage of urea in it. On the 

 other hand, when the proportion of total kidney weight remain- 

 ing was only a quarter or less, death occurred in from one to six 

 weeks, and appeared to be due to inanition associated with great 

 muscular wasting and thirst. The blood showed the same 

 hydrsemia, but a much greater increase in the percentage of urea. 

 The urine was of the same character, but the total excretion of 

 water and urea was greater. Increase of nitrogenous food had 

 the same effect as before. The increased daily output of urea was 

 due to the breaking down of the muscles and other nitrogenous 

 tissues, as shown by the inanition and wasting. But the increased 

 nitrogenous excretion was unable to keep pace with the breaking 

 down of the tissues, for the percentage of nitrogenous extractives 

 in the blood and tissues rose considerably. This failure of the 

 kidney fragment to excrete sufficient nitrogen was not due to 

 circulatory failure, because the arterial blood pressure remained 



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