44 SCIENCE PROGRESS 



the adjustments of metabolism, it is by no means certain that 

 they influence the equilibrium of carbohydrate so greatly 

 as the theory demands. The discussion, at any rate, has taken 

 us away from the teachings of Pavy, who had but little oppor- 

 tunity of appraising so recent a view. 



There is a form of glycosuria, experimentally induced, which 

 has been much made use of in laboratory studies but which 

 differs in a fundamental aspect from the vast majority of cases 

 of spontaneous diabetes. I must refer to it before closing be- 

 cause it occupied Pavy's attention and lent some support to his 

 views. When the substance phloridzin, a crystalline glucoside, 

 is administered to animals, intense glycosuria is induced. The 

 great difference between this and other forms of diabetes is in 

 the amount of sugar in the blood, which becomes less than normal 

 under the influence of the drug, instead of greater. Although 

 there is still obscurity with regard to the exact mechanism 

 of the action of this drug, there is no doubt that its seat is in the 

 kidney. The view with regard to phloridzin diabetes which has 

 been generally accepted is that of Von Mering, who discovered 

 the phenomenon. He held that the effect of the drug is to in- 

 crease the permeability of the kidneys for sugar. This leads to 

 a lowering of concentration in the blood and a liberation of 

 sugar from the organs to restore the deficiency. So long as the 

 drug is in action, this process is continuous and leads to a large 

 excretion of sugar. 



It is clear, from what has gone before, that such a view 

 would not square with Pavy's fundamental conception. In 

 1903, in conjunction with Brodie and Siau, he published some 

 very interesting experiments which showed that a kidney 

 removed from the body and perfused with blood containing 

 phloridzin could excrete a quasi-urinary fluid containing more 

 sugar than was lost by the blood perfused. Other experiments 

 showed that if all the abdominal viscera were removed from an 

 anaesthetised animal with the exception of the kidneys, the in- 

 jection of phloridzin still produces a notable excretion of sugar. 



Altogether these experiments seem to establish the fact that 

 sugar is formed in the kidney itself and Pavy's view was that 

 under the influence of the drug the renal cells acquire a 

 power of splitting off sugar from some complex in the blood. 

 Certainly these experiments offer the best evidence available 

 for the circulation of sugar in some definite combination. 



