366 



inferring that the renal-portal veins convey blood to a functional part 

 of the kidney, in this case the tubules. 



GuRWiTSCH (7), among a number of other experiments, shewed 

 that a ligature of the entire portal supply of one kidney, reduced the 

 secretion of that organ, while its fellow not so treated kept up a 

 normal flow of urine. 



Finally, the perfusion experiments of Cullis (6) have produced 

 some very striking evidence. The experiments which give the strongest 

 grounds for regarding the kidney circulation as having a portal function 

 are those in which the perfusion was arterial, i. e. through the renal 

 arteries, or venous, i. e. through the renal -portal vein. Two of the 

 observations from venous perfusion are summed up in the following 

 words: "In extension of this result I have found that if from the start 

 of the perfusion (with urea) the kidney is supplied with fluid from the 

 renal portal vein only, there is invariably a secretion" and "when 

 strong solutions of urea are perfused, the main difierence observed 

 has been, that, on a venous perfusion only a very copious flow of 

 urine occurs". Some of the results obtained by perfusion of the renal- 

 portal vein were negative; but a satisfactory explanation of some of 

 these was afterwards given thus: "The results obtained with (Sodium) 

 nitrate first suggested the possibility that though flow of urine may 

 stop when the glomeruli are cut out, secretion may still continue for 

 a time through the tubules, thus leading to the accumulation of a 

 concentrated solution in the tubule, which then stops further secretion." 

 Experiments were then performed which shewed that this was the case. 

 Arterial perfusions of Sodium phosphate, sulphate and nitrate, in which 

 the arterial blood supply was replaced by oxygenated Ringer's solution 

 with one of the above salts in it, led to a secretion of urine, the 

 normal excretory part of which was therefore supplied from the portal 

 blood. 



Conclusion. 

 To recapitulate : I have examined the a priori arguments adduced 

 by Woodland in support of his theory of the non- portal nature of 

 the kidney circulation in the frog, and found them inconclusive; and 

 in addition have brought forward against this view and in support of 

 the portal nature of this circulation the following morphological and 

 physiological facts. 



1) In abnormalities the kidney supplied by a portal vein is con- 

 siderably larger than its fellow not so supplied. 



2) There is a similar anatomical relation between the blood and 



