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



arterial injection fluid, whereas the intertubular capillaries showed, some the 

 arterial fluid, some the venous, and some a mixture of both. We confirmed 

 Beddard's observation that the perfusion of Berlin blue solutions at a low 

 pressure through the renal portal vein leaves the glomeruli completely 

 uninjected. We found, however, that if the venous perfusion were made 

 under an abnormally high pressure {e.g. 35 cm. of water) the coloured 

 solution eventually made its way into some, at least, of the glomeruli. It 

 was further shown by arterial perfusion with Berlin blue that the glomeruli 

 will withstand a perfusion pressure of at least 40 cm. of water. 



Other evidence that the renal portal blood supplies the whole of the 

 tubules was obtained by perfusing 1/10,000 mercuric chloride at 10 cm. 

 pressure for three to five minutes through the renal portal vein, and then 

 perfusing through the vein under the same pressure first saline solution for 

 a few minutes and then a very weak solution of ammonium sulphide in 

 saline solution. The whole of the tubules showed a deposit of mercuric 

 sulphide while the glomeruli remained free from it in the vast majority of 

 cases. It seems clear, therefore, that a poison reaching the kidney by way of 

 the renal portal vein will come in contact with the whole of the tubules and 

 yet leave the glomeruli practically or quite intact. The only risk is that 

 a diffusible poison, if not quickly rendered inert or washed out of the 

 kidney, may gradually reach the glomeruli by direct diffusion. This risk is 

 minimised by having a simultaneous arterial perfusion and by using the 

 poison in a concentration which is just adequate to kill the tubules when 

 brought into immediate contact with them. Whether the arterial blood 

 supply alone provides the tubules with a sufficiency of oxygen has yet to be 

 determined by experiments ou the living animal. It is known, however, that 

 the venous supply alone will maintain their nutrition in the living frog 

 provided that the frog is kept in an atmosphere of oxygen. There can be 

 little doubt that in these experiments, in which the perfusing fluid was 

 fully oxygenated, both the supply of oxygen to the tubules in a venous 

 perfusion and that to the glomeruli in an arterial perfusion were amply 

 sufficient to maintain their vitality so long as the rate of perfusion remained 

 normal. 



Experimental. — In most of the experiments to be described the perfusion 

 was made with normal or hypotonic Binger's solution, and the experiments 

 made with hypertonic Binger's solution will only be referred to incidentally. 



(1) The Normal Kidney. — The rate of arterial perfusion varies considerably 

 in different experiments, doubtless as a result of the varying tone of the 

 glomerular vessels, and more particularly the efferent vessels ; it is apt also 

 to decrease in the course of a single experiment. Since the oxygen supply 



