400 Transactions of the Canadian Institute [vol. ix 



of phloridzin and in the rabbi c's kidney in dextrose diuresis. A sub- 

 stance that promotes very vigorous diuresis may, directly or indirectly, 

 influence unequally the tension of the lymph and the tension on the 

 basal and free surfaces of the excreting renal cells. This would explain 

 many differences observed between the renal cells in very marked 

 diuresis and the renal cells engaged in ordinary activity. In the renal 

 cells in excessive diuresis, as already described, the condensations are 

 irregular, occurring not rarely on the surface of the cell nuclei and the 

 lateral walls of the cells, particularly so in the cases in which injections of 

 potassium salts, and especially the iodide, had been given. Similar but 

 less striking condensations of potassium were found in kidneys in diuresis 

 caused by injections of sodium sulphate. 



Potassium salts were occasionally found in the lumina of the tubules 

 in all preparations, but particularly in those from the rabbit that had 

 been subjected to the action of dextrose after the animal was pithed. 

 In these the amount of glomerular fluid formed was diminished, and, in 

 consequence, the potassium diffused into the lumen of the tubule from 

 the adjacent condensation layer was to a certain extent retained in the 

 fluid of the lumen. Where, therefore, potassium salts were found in the 

 lumina of some of the renal tubules of unpithed animals, it may be 

 reasonably explained as due to diminished activity on the part of their 

 glomeruli. 



No evidence of the occurrence of potassium salts in the free space of 

 the glomerular capsule was obtained. 



Whether potassium in its salts or compounds serves in the kidney any 

 special purpose in renal excretion is a question which presents itself. 

 The potassium of the condensation layeis, abundant though it is, cannot 

 be regarded as the whole of the element which obtains in the kidney, for 

 although the hexanitrite reagent is an exceedingly sensitive one for 

 potassium, it cannot demonstrate what is below the limit of sensitivity. 

 Indeed, the very fact that in the cells of the convoluted tubules which 

 show condensation of potassium in the cytoplasm adjacent to the lumen 

 borders, the remaining cytoplasm itself does not give a reaction for 

 potassium is evidence of this, for the condensation itself predicates a 

 certain concentration, although excessively dilute, in the fluid system 

 constituted by the cell as a whole. 



Support for the view that potassium serves a special function in the 

 kidney is afforded by analyses which the author made and which show 

 the amount of the sodium and potassium in the organ. For this purpose 

 frogs and dogs were used. In the case of the frog a large number of 

 kidneys removed from recently killed animals were collected in bulk to 

 weigh 17-22 grm.; each mass thus made was carefully dried in a platinum 



