Apeil 16, 1915] 



SCIENCE 



585 



kidney function die? Since nephrectomized 

 animals regularly show a progressive loss in 

 weight, and since this is, in the main, only 

 water, a first reason for death might reside in 

 the gradual drying-out of the tissues. Whether 

 the animal is fed or whether it is starved, a 

 certain minimum of necessary chemical 

 changes goes on, which continue, as long as the 

 animal remains alive. A second reason for 

 the death of the kidneyless animal resides, 

 therefore, in the accumulation of metabolic 

 products within the organism which normally 

 are thrown off in the urine. A third reason 

 for death (but one for which at present we 

 lack every experimental proof) might reside 

 in the loss of some internal secretion produced 

 by the kidney and necessary for life of the 

 organism as a whole. 



The analysis of the conditions necessary for 

 a proper exhibition of kidney activity would 

 seem to indicate that it is the primary func- 

 tion of the kidney to secrete water. It secretes 

 water in proportion to the amount brought it 

 in a free state in the arterial blood stream. 

 As this free water passes down the uriniferous 

 tubules it leaches out of the cells bordering it 

 and constituting the kidney parenchjona the 

 dissolved substances which give urine its dis- 

 tinguishing characteristics (urea, ammonia, 

 creatin, sugar, salts, etc.) which substances 

 originally diffused into the kidney parenchyma 

 from the blood stream. 



If we ignore the matter of an internal 

 secretion, these considerations, if correct, com- 

 pel the conclusion that the kidney is of im- 

 portance to the animal, first, because it is an 

 organ through which water may be lost when 

 present in amounts over and above those neces- 

 sary to saturate the tissues (saturate the hy- 

 drophilic colloids) ; and second, because this 

 loss of water makes possible the loss of certain 

 dissolved substances which appear in even 

 normal metabolism. 



The steady loss of water in the ill or by a 

 nephrectomized rabbit, for example, need not, 

 of course, be an important element in the 

 causation of death. Care in the administra- 

 tion of water by rectum or subcutaneously can 

 overcome this. Nor is the inability to lose 

 much water quickly, as by the kidney route, 



alone an insurmountable cause for death. 

 Even under physiological conditions the 

 human being not only can but does lose more 

 water from the lungs and skin than through 

 the kidneys. What is missing is the possibil- 

 ity of losing along with the water the various 

 dissolved substances which appear as the prod- 

 ucts of metabolism. If this reasoning is 

 sound it is to be expected that, other things 

 being equal, animals deprived of their Icidney 

 function should live the longer the "better the 

 possihilities of securing an adequate loss of dis- 

 solved suhstances along with their water elimi- 

 nation. The facts bear this out. The furred 

 animals, for example, which lose no water 

 except through the lungs, after the kidneys are 

 removed, survive this operation little more 

 than four to eight days. The human species 

 with its ability to sweat tolerates loss of 

 kidney function some six to twelve days. 

 James Taggart Priestley has reported the case 

 of a patient who lived 22 days with complete 

 suppression of urine. It is considerations of 

 this kind that have prompted clinical workers 

 to resort to sweating and catharsis by way of 

 transferring to the skin and gastro-intestinal 

 tract the functions which are ordinarily sub- 

 served by the kidney whenever this organ is 

 pathologically affected. But even when ad- 

 vantage has been taken of such potentialities, 

 the lives of patients with complete loss of 

 urinary function have not been long. 



It occurred to me that it ought to be possible 

 to observe a greater span of life in animals 

 after complete suppression of kidney function 

 if only it were possible on the one hand to 

 cover the needs for water absorption and water 

 loss, while on the other, provision were made 

 for an adequate loss of the products of metab- 

 olism which normally are leached out by the 

 water which passes through the kidney. 



Such conditions are satisfied in the case of 

 the frog. Not only does the frog cover its daily 

 needs for water (saturate its body colloids) by 

 spending a part of its time in the water, but 

 it also loses under the same circumstances the 

 same group of materials which ordinarily give 

 the urine its characteristic composition. The 

 problem is similar to that in man, who loses 

 the same dissolved substances in the sweat that 



