MECHANISM OF RENAL SECRETION 39 



tive findings for iron in the glomeruli and Bowman's capsule, 

 but records iron as present in the lumen of the convoluted and 

 collecting tubules and in the cytoplasm of the cells of the con- 

 voluted tubules, along their free edge. As will be seen by the 

 results described below, such findings are entirely in accord with 

 those of our experiments. The chief, and serious objection to 

 this work of Glaevecke lies in the method of administration of 

 the salt. The subcutaneous injection does not allow of any 

 accurate time relationship. An extra and unnecessary unknown 

 factor is introduced in this way, namely, the rate of absorption 

 of the salt into the blood stream and the equally indefinite 

 period of administration to the blood. Throughout our experi- 

 ments intravenous injection has been employed. 



Kobert (44) also, in his study of the pharmacology of iron, has 

 attempted an explanation of the mechanism of its elimination 

 from the body, but his renal investigations have been so incom- 

 plete and inconclusive that the conclusions drawn are really not 

 warranted. More will be said of this work at a later point. 

 Quincke (25) also used iron. 



The iron salt first employed in this investigation was the simple 

 ferric citrate in the form of brown scales. But the salt is only 

 sparingly soluble and required boiling before any clear solution 

 could be obtained. Such a solution w^as always very dilute. 

 As such a dilute solution requires the injection of large amounts 

 of fluid to carry sufficient iron for histologic work, it would alter 

 materially the activity of the kidney through its diuretic action. 

 Therefore an attempt was made to use the compound salt, ferric 

 ammonium citrate. The Kahlbaum preparation of the brown 

 scales was first used. It was found to be freely soluble in water 

 and in doses of 0.15 gram per kilo body weight was not notice- 

 ably toxic. But a series of experiments (K9, Kll, K12, K13, 

 and K14) of injection with larger doses (0.4 gram per kilo weight) 

 demonstrated that the dose was invariably fatal in from one-half 

 to nine hours. Repeated injections of the smaller dose of 0.2 

 gram per kilo weight were not fatal, but they led to albuminuria 

 and the presence of casts in the urine. Therefore, this form of 

 iron had to be discarded because of its toxic properties. We 



THE AMERICAN JOJRNAL OF ANATOMY, VOL. 29, NO. 1 



