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Messrs. Bainbridge, Collins, and Menzies. [Mar. 27 y 



(2) The Bead Kidney. — The vitality of the kidney was destroyed by 

 perfusing it through the aorta either with weak (1/10,000) corrosive- 

 sublimate or with boiled Ringer's solution. After the former procedure the 

 arterial perfusion with Ringer's solution was resumed under normal pressure. 

 The rate of perfusion and the amount of urine obtained were always much 

 less than in the normal kidney, and sometimes, with a very slow perfusion 

 rate, the flow of urine entirely ceased. The urine was usually isotonic with, 

 but occasionally hypertonic to, the perfusing fluid, the latter only in experi- 

 ments in which the formation of urine was extremely slow and scanty. 



(3) Since the urine obtained in all these experiments comes solely from 

 the glomeruli (the tubules secrete no urine), it is natural to suppose that the 

 difference in the character of the urine formed by the intact and dead kidneys 

 respectively depends upon one of two causes. On the one hand, the glomeruli 

 may normally form by filtration a urine which is isotonic with the perfusing 

 fluid, and the absorption of salt may be effected by the tubules as the 

 glomerular filtrate passes along them. On the other hand, the tubules may 

 possess no absorptive power for sodium chloride or other salts, and the 

 glomeruli may possess the capacity to secrete a hypotonic urine. In 

 attempting to decide between these two possibilities, two methods have- 

 been used. 



(a) The tubules were poisoned by perfusing 1/10,000 mercuric chloride 

 through the renal portal vein for three to five minutes, and then Ringer's 

 solution was perfused for a few minutes through the renal portal veins, to 

 wash away the mercury in the blood-vessels. The arterial perfusion of 

 oxygenated Ringer was maintained throughout the experiment. The urine 

 obtained both before and after the poisoning of the tubules was examined, 

 and at the end of the experiment the mercury was fixed in the tubule cells 

 by perfusing dilute ammonium sulphide through the renal portal veins, 

 and the kidneys were examined histologically. It was found in most of 

 the experiments that the glomeruli remained free from j mercury, and that 

 mercuric sulphide was present in the whole of the tubules. This was also 

 the case in control experiments in which the mercury was fixed by ammonium 

 sulphide immediately after it had been perfused through the renal portal 

 vessels. Experiments in which mercury was present in the glomeruli were- 

 rejected. The following protocol illustrates the character of these experi- 

 ments : — 



