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Experiments on the Kidneys of the Frog. (Preliminary 

 Communication. ) 

 By F. A. Baikbridge, S. H. Collins, and J. A. Menzies. 



(Communicated by Prof. C. J. Martin, F.R.S. Received March 27, — Read 



April 24, 1913.) 



Introduction. 



As is well known, the glomeruli of the frog's kidney are supplied with 

 blood only by the renal arteries, whereas the renal tubules have a double 

 supply. On the one hand, they receive blood by way of the renal portal 

 veins ; on the other hand, the efferent vessels from the glomeruli open into 

 the capillary network round the tubules. The whole of the tubule receives 

 blood from each of these two sources, so that the capillary network around 

 the tubules can be fully injected either from the renal arteries or from the 

 renal portal veins. Taking advantage of this fact it has been shown by 

 Beddard and one of us (F. A. B.) that after complete occlusion of the 

 glomeruli the tubules, when adequately supplied with oxygen, maintain 

 their normal histological appearance, and may secrete urine. In the 

 present experiments an attempt has been made to determine the function 

 of the glomerulus and to ascertain whether the tubules possess the capacity 

 to absorb water and solids. 



Methods. 



1. Experimental. — All the experiments were carried out on fully pithed 

 frogs. In the earlier experiments the following method was adopted: — 

 Ligatures were tied round the fore limbs, the heart was exposed, and the 

 right aortic arch tied off. The ventricle and auricles were freely opened, 

 and a cannula connected with a perfusion bottle was tied into the left 

 aortic arch. The arterial perfusion was started at once, and the ventricle 

 and auricles were then excised. This procedure was carried out as quickly 

 as possible after the frog was pithed, and usually took five or six minutes. 

 It is of importance to commence the arterial perfusion at the earliest 

 possible moment. When most of the blood was washed out of the circu- 

 lation the anterior abdominal vein was tied in two places and divided, the 

 hind legs were tied off, and a cannula was placed in the inferior end of the 

 anterior abdominal vein and connected with a perfusion bottle. The fluid 

 leaving the kidneys was collected by means of a cannula placed in the 

 beginning of the vena cava just beyond its origin from the renal veins. 

 Finally, cannulse were placed in the ureters. This latter operation was 



