44 E. J. STIEGLITZ 



elimination through a study of the secretory curves obtained by 

 catheterization and of the effect of the iron injections upon the 

 circulation. Series IV represent the investigations dealing with 

 sodium ferrocyanide in contradistinction to the fate of ferric 

 iron. 



In the next group, series V, experimental nephritides, as pro- 

 duced by the almost specific renal poisons, tartrates, chromates, 

 mercuric bichloride, uranium salts, and diphtheria toxin, are 

 studied as to their effect upon the elimination of iron and it is 

 attempted, through the localized pathology to support further 

 the conception of localized, specialized, and specific secretion by 

 the various units of the uriniferous tubule. 



RESULTS 

 Series I 



In this group of experiments iron salts, usually the green ferric 

 ammonium citrate, were injected intravenously into rabbits 

 and the animals killed at time intervals varying from two to 

 five hundred and sixty (560) minutes later. The kidneys were 

 immediately fixed and histologic preparations demonstrating the 

 iron in the form of Prussian blue prepared. 



The histologic localization of the iron in the kidney showed 

 several constant characteristics, noted in every, preparation. 

 The first, most conspicuous and uniform factor was that the iron 

 tended to be concentrated along the free border of the cells next 

 to the lumen. In the earlier stages (two and three minutes) 

 this was not so marked, but those preparations taken from 

 experiments where the interval had been over thirty minutes 

 showed the concentration quite conspicuously. The second 

 common characteristic was that, in no case, if the technique of 

 staining was carefully carried out, was there any evidence of 

 iron in the connective tissue or any diffuse staining with the 

 reagents. In regard to this notable absence of iron in the inter- 

 stitial tissues a very interesting side issue developed, inasmuch 

 as sodium ferrocyanide was demonstrated to be present (Prussian 

 blue precipitate with trichloracetic acid and ferric chloride or 



