84 E. J. STIEGLITZ 



g. During the period of iron elimination the specific gravity 

 of the urine is distinctly lowered, demonstrating that less solids 

 are being secreted at that time. 



3. During the period of iron secretion there is an initial tran- 

 sient rise in the rate of water excretion, followed by a consider- 

 able inhibition which persists until the quantity of iron in the 

 urine declines. 



a. The initial diuresis is in accord with the physicochemical 

 experiments of Fischer. 



b. The inhibition to water secretion is due to the rapid and 

 thorough intracellular localization of the ferric ions which are 

 active in preventing colloid hydration. 



c. The inhibition to water elimination cannot be explained on 

 a basis of vascular depressor action of the drug or to the binding 

 of 'free' water in the blood plasma. 



d. Iron does not appear in the bladder urine earher than ten 

 minutes following intravenous injection of the salt. 



e. With the simultaneous injection of caffeine similar results 

 occur except that the initial and final diuresis are more marked 

 and the duration of iron elimination is diminished. 



4. The ferrocyanide complex ion is very diffusely distributed 

 in the body. 



a. The actions of this compound differ from those of ferric 

 iron in the diffuse distribution, in the longer period of elimina- 

 tion and in the slighter effect upon the body colloids in connec- 

 tion with the adsorption of water by them. 



b. The differences in behavior are due to the complex ferro- 

 cyanide ion. 



5. The presence of a distinct acute local tubular nephritis 

 greatly interfered with the secretion of iron. 



a. Uranium nephritis, tartrate nephritis, chromate nephritis, 

 and sublimate nephritis inhibit a block iron elimination. 



b. Diphtheria toxin nephritis, which is primarily vascular 

 (glomerular), produces very little interference with the elimina- 

 tion of iron. 



