1912] On the Distribution of Potassium in Renal Cells 393 



nized as migrating leucocytes (Fig. 7a), protruding red blood cells (Fig. 76) 

 and epithelial cells (Fig. 7c). These were found in restricted regions 

 of the kidney where large numbers of leucocytes had gathered, the 

 excess of diuretic apparently having acted as an irritant producing a 

 necrosis similar to the condition found in preparations from the kidney 

 of a dog which had been treated with cantharidin. Whether the 

 striking aggregation of potassium salts on the surface of these structures 

 is due to precipitation or condensation it is difficult to say. It appears 

 to be analogous to that found by Professor Macallum in the root hairs 

 of Equisetum arvense and in the outgrowing processes of conjugating 

 Spirogyra.^ 



Where the excessive diuresis was occasioned by injection of potas- 

 sium salts, e.g., potassium phosphate, a similar distribution was observed 

 (Fig. 8), accompanied, as one would expect, by an increase in the amount 

 of potassium present. Not only were the intercellular membranes and 

 the surfaces of the nuclei heavily charged, but the potassium was 

 frequently found throughout the cytoplasm as well, either in a sort of 

 network, or else distributed faiily uniformly. The rapidity with which 

 an iodide penetrates tissues was demonstrated in one animal injected 

 with potassium iodide and killed five minutes later. The heavily loaded 

 tubules showed different states of activity. In the inactive tubules, as 

 illustrated in Fig. 9, the potassium iodide was more or less irregularly 

 distributed, but in the very active tubule the salt was chiefly condensed 

 on the external surfaces of the tubules and in the cell at the lumen 

 border (Fig. 10). 



The preparations from the kidney of a dog which had been under 

 A.C.E. anaesthesia for two hours, and in which the kidney would thus be 

 in a fair state of activity, illustrated the peripheral and central condensa- 

 tions most strikingly (Fig. 11). The peripheral condensation was more 

 frequent than the central, the latter being oftener seen when the urine 

 flow was checked by pithing. Where the tubules had been thrown into 

 activity by phloridzin the same distribution was found, differing only in 

 that the condensations of potassium were distributed more uniformly 

 about the tubules and a larger proportion of the tubules manifested the 

 condensation (Fig. 12). It is difficult to illustrate this, as one only 

 comes to this conclusion after examining a considerable number of 

 preparations, but I have endeavoured to select tubules representative 

 of each condition. In these preparations, in all of which the different 

 regions of the kidney could be recognized, the localization was found in 

 the convoluted tubules and in the loops of Henle, but in no case was a 

 distinct localization evident in the region of the collecting tubules. 

 Owing to the unstained nature of the preparations it was impossible to 



