404 EXCRETION. 



place, it is well known that the operation of tying the ureters is followed by an immense 

 pressure of urine in the kidneys, which not only disturbs the eliminative action of these 

 organs, but affects most seriously the general functions. Since the influence of the ner- 

 vous system upon the secretions has been closely studied, it is evident that the pain and 

 disturbance consequent upon the accumulation of urine above the ligated ureters must 

 have an important reflex action upon the secretions; and this would probably inter- 

 fere with the vicarious elimination of urea and other excrementitious principles by 

 the stomach and intestines. It is well known to practical physicians that an arrest 

 of these secretions, in cases of organic disease of the kidneys, is liable to be followed 

 immediately by evidences of uraemia, and that grave ursemic symptoms are frequently 

 relieved by the administration of remedies that act promptly and powerfully upon the 

 intestinal canal. As an additional evidence of the great disturbance of the system aside 

 from the mere accumulation of excrementitious principles in the blood which must 

 result from tying the ureters, we have the intense distress and general prostration, 

 always so prominent in cases of nephritic colic in which there may be merely temporary 

 obstruction of one ureter. 



From a careful review of the important facts bearing upon the question under con- 

 sideration, there does not seem to be any valid ground for a change in our ideas concern- 

 ing the mode of elimination of urea and the other important excrementitious constituents 

 of the urine. There is every reason to suppose that these principles are produced in 

 the various tissues and organs of the body during the process of disassimilation, are 

 taken up by the blood, and are simply separated from the blood by the kidneys. There 

 may be unimportant modifications of some of these principles in the kidneys or in the 

 urine, such as the conversion of a certain amount of creatine into creatinine, but the great 

 mass of excrementitious matter is separated from the blood by the kidneys unchanged. 



Extirpation of one kidney from a living animal is not necessarily fatal. We have fre- 

 quently performed this operation as a class-demonstration, and have kept the animal for 

 weeks and months, without observing any indications of disturbance in the eliminative 

 functions. If the operation be carefully performed, the wound will generally heal with- 

 out difficulty, and in most instances the remaining kidney seems sufficient for the elimi- 

 nation of urine for an indefinite period. In all of our experiments, save one, the ani- 

 mals, killed long after the wound had healed, never presented any marked symptoms of 

 retention of excrementitious matters in the blood. It is a noticeable fact, however, 

 that in many instances they showed a marked change in disposition, and the appetite 

 became voracious and unnatural. These animals would sometimes eat fa3ces, the flesh 

 of dogs, etc., and, in short, presented certain of the phenomena so frequently observed 

 after extirpation of the spleen. After extirpation of one kidney, it has been observed 

 that the remaining kidney increases in weight, although recent investigations show that 

 this is due mainly to an increase in the amount of blood, lymph, and urinary princi- 

 ples, and not to a new development of renal tissue. It is reasonable to suppose that 

 Nature has provided, in the kidneys, more working substance than is ordinarily required 

 for the elimination of the excrementitious constituents of the urine ; and that, even 

 when one kidney is removed, the other is competent to eliminate the amount of excre- 

 mentitious matter that is produced, under ordinary conditions of the system. The 

 exceptional experiment in which the animal died after extirpation of one kidney is quite 

 interesting : October 6, 1864, we removed one kidney from a small cur-dog, about 

 nine months old, by an incision in the lumbar region. The animal did not appear 

 to suffer from the operation, and the wound healed kindly. The only marked effects 

 were great irritability of disposition and an exaggerated and perverted appetite. He 

 would attack the other dogs in the laboratory without provocation, and would eat with 

 avidity, faeces, putrid dog's flesh, and articles which the other animals would not touch, 

 and which he did not eat before the operation. On the morning of November 18th, 

 forty-three days after the operation, the dog appeared to be uneasy, cried frequently, and 



