656 THE SECRETION OF URINE. 



periments by Adami, 1 working in Heidenhain's laboratory, has shown 

 that in the frog it is impossible to cut off the blood supply to the 

 glomeruli by ligaturing the renal arteries. In fact, after this operation, 

 fully half of the glomeruli may be injected from the aorta, owing to 

 the free anastomoses between the renal artery and the branches of 

 the ovarian arteries and the renal portal vein, and it is difficult to 

 understand how ISTussbaum can have obtained the very definite results 

 described by him. These, therefore, in spite of the ingenuity of the 

 methods employed, must be discredited in any discussion concerning the 

 functions of the various parts of the kidney tubule. 



Experiments of Ribbert. A bold attempt to experimentally disso- 

 ciate the activities of the two portion^ of the urinary tubule was made 

 by Eibbert, 2 who adopted the method of excising as far as possible the 

 medulla of the kidney, so as to obtain the glomerular secretion after 

 it had passed through only the first convoluted tubules. This opera- 

 tion is only possible in animals such as the rabbit, in which the renal 

 medulla is made up of one Malpighian pyramid. It was carried out 

 in the following way: One kidney having been exposed from the 

 back, was cut in two by an incision at right angles to the long diameter 

 of the organ, extending into the pelvis. By means of a gouge, as much 

 as possible of the pyramid internal to the boundary zone was removed. 

 The two halves of the kidney were then placed together and secured 

 by sutures, and the other kidney totally excised. Eibbert found that 

 such animals during the next twelve to twenty-four hours secreted a 

 much larger quantity of urine than they had previously done. The 

 urine was more dilute and much lighter in colour than the urine of 

 rabbits under normal conditions. No analyses, however, of the fluid 

 were made. Eibbert interprets these results as confirming Ludwig's 

 hypothesis. But apart from the increased quantity, which does not 

 seem to me to be definitely established by Eibbert's experiments, the 

 production of a more dilute urine would be expected on either 

 hypothesis, whether we assume with Ludwig that the tubules absorb 

 water from the urine, or with Heidenhain that they excrete solid 

 substances into the urine. 



Experiments of Bradford. The very insufficient description of 

 his experiments given by Eibbert might incline us to discredit them 

 altogether, were it not that somewhat analogous results have been 

 obtained by Bradford. 3 This observer found that extirpation of one 

 kidney, combined with excision of a large wedge-shaped piece from the 

 other kidney, might bring about one of two results 



1. If the amount of kidney substance left amounted to one quarter 

 of the weight of the two kidneys, the animals (dogs) lived a considerable 

 time, but suffered from hydruria, i.e. the quantity of urine excreted was 

 largely increased, but the excretion of urea remained unchanged, so 

 that the urine was much more dilute than before. 



2. If the amount of kidney left was less than one-sixth of the total 

 kidney substance, polyuria was produced, i.e. a large increase in the 

 excretion of water as well as of urea. This increased production of urea 

 was due to a rapid wasting of the proteid constituents, and especially of 

 the muscles of the body, so that the animals died in a short time in a 



1 Journ. PhysioL, Cambridge and London, 1885, vol. vi. p. 382. 



2 Virchow's Archiv, 1883, Bd. xciii. S. 169. 



3 Proc. Roy. Soc. London, 1892, vol. li. 



