46 E. J. STIEGLITZ 



of Henle's loop, where there was some slight diffuse cytoplasmic stain- 

 ing. In the medulla there was iron present in the lumina of the collect- 

 ing tubules and blood-vessels. 



Two and one-half minutes (K42). Adult female rabbit. Weight = 

 1970 grams. Injected 0.4 gram' green ferric ammonium citrate intra- 

 venously. Animal killed two and one-half minutes later. Kidneys 

 fixed in: 



95 per cent alcohol. 



Zenker's fluid. 

 The urine in the bladder at death w^as negative for iron. 

 Histologic findings: The preparations from this experiment gave 

 nearly the same picture as those from experiment K35. Iron was 

 found in considerable amount in the blood-vessels, but not conspic- 

 uously in the glomerular tufts as in the previous experiment. In the 

 convoluted tubules, the iron was in every location in the cells in dif- 

 ferent individual tubules. Sometimes it was nearly confined to the 

 border of the cells approximating the lumen, and in other examples it 

 was to be found at the opposite periphery of the cell. There was some 

 iron in the lumen of the convoluted tubules, in the form of distinct 

 granules. In the medulla the iron was confined to the lumen of the 

 collecting tubules and the blood-vessels. 



Three minutes {K38). Adult female rabbit. Weight = 2300 grams. 

 Injected 0.44 gram green ferric ammonium citrate intravenously. 

 Animal killed three minutes after injection. Kidneys fixed in: 



95 per cent alcohol. 



Zenker's fluid. 



The urine in the bladder at the time of death was negative for iron. 



Histologic findings: In this specimen there was again considerable 



Prussian blue in the blood-vessels, but not so much in the glomerular 



tufts as before. In the case of the convoluted tubules, the iron was 



nearly entirely confined to the peripheral portion of the cytoplasm, 



aw^ay from the lumen. There was some iron in the lumen of the 



tubules and in the medullar}'' rays and collecting tubules of the medulla. 



Ten minutes {K32). Small male rabbit. Weight = 1620 grams. 



Injected 0.3 gram green ferric ammonium citrate, plus 0.3 gram sodium 



ferrocyanide intravenously. Animal killed ten minutes later. Ivid- 



neys fixed in: 



95 per cent alcohol. 



5 per cent trichloracetic acid. 



Zenker's fluid plus trichloracetic acid. 



Carnoy's fluid plus crystals of trichloracetic acid. 

 The urine in the bladder at death was positive for iron. 

 Histologic findings: In both the 95 per cent alcohol and 5 per cent 

 trichloracetic acid specimens of this experiment nearl}^ all the iron 

 was present in the lumen of the collecting tubules and those of the 

 medullary raj-^s. There was some little iron to be seen in the blood- 

 vessels. The iron in the convoluted tubules was present in the cyto- 

 plasm of the cells, especially near the free border of the cells at the 



