52 E. J. STIEGLITZ 



in the form of granular masses in the kimina of a few of the 

 tubules of the medullary rays, somewhat after the nature of early 

 casts. In a few cases small scattered granules of blue were to 

 be seen in the cytoplasm of the cells of the convoluted tubules. 

 The liver preparations w^ere negative for iron, but the Kupffer 

 cells were more numerous in the stellate form than normally 

 found (51, 52). In the spleen, the macrophages contained much 

 iron, but the splenic corpuscles were free thereof. In K52, 

 where the animal was killed twenty-four hours after the injec- 

 tion of a corresponding dose, there was not apparently any more 

 iron present. Therefore the rate of disappearance of this iron 

 must be a slow one. 



Any retention of the salt in the secretory cells would indicate 

 that the cells are not able to pass on all the iron as they receive 

 it, and that therefore, if the cells were made to receive still more 

 iron, the retention should be >^cumulative. In experiment K30 

 three injections of the less toxic green ferric ammonium citrate 

 were given in intervals of about thirty-six hours, thus permitting 

 the urine to be free of iron for some twenty-four to thirty hours 

 before the next injection. The animal was killed ninety- two 

 hours after the last injection, or seventy- two hours after the 

 urine had become negative. Histologically, a considerable reten- 

 tion of iron was demonstrated. The iron was confined to the 

 cytoplasm of the cells of the convoluted tubules. It was again 

 noted that certain tubules were entirely free, while others con- 

 tained considerable quantities of Prussian blue. The phagocytic 

 cells of Kupffer in the liver and the splenic macrophages also 

 contained much of the reagent. Experiments K87, K88, K89, 

 and K91 are of a similar nature. The routine Zenker control 

 fixation revealed the kidneys of K87 and especially K88 to be 

 pathologic, the former showing focal and diffuse areas of round- 

 cell infiltration and the latter a distinct chronic fibrous inter- 

 stitial nephritis. Therefore these two experiments must be 

 discarded. In K89, in which the animal had received four injec- 

 tions of iron, the cells of the convoluted tubules were found to 

 be diffusely blue, with a slight concentration of the color at the 

 free margin of the cells, and the findings in K91, after the same 



