44 INORGANIC FOODSTUFFS 



by the administration of inorganic salts of iron, and often with beneficial 

 effect. For long it was thought, without any question, that the salts 

 of iron so administered were absorbed and that the beneficial effect of 

 the medicament was due to the replacement of the iron in the blood by 

 the iron so administered. Doubt was thrown upon this explanation 

 by the discovery that iron is eliminated from the body in the feces. 

 Doses of inorganic salts of iron, administered to healthy individuals, 

 were recovered apparently unaltered in the feces, and from this fact 

 the erroneous conclusion was drawn that inorganic salts of iron are not 

 absorbed. The beneficial effects of iron in anemia were either denied, 

 a denial in which practising physicians declined to share, or else 

 accounted for by the irritant action of the salts of iron upon the epithe- 

 lium of the intestinal tract. A mild irritation has a well-known " tonic" 

 effect which is rather difficult to define in precise terms; but which is 

 frequently manifested, not only by increased activity of the tissues 

 which are stimulated, but also of other and sometimes distant tissue. 

 The beneficial effects of iron were therefore attributed to increased 

 activity of the tissues resulting in increased assimilation and utilization 

 of the organically combined iron in the diet and not to direct assimi- 

 lation of the iron administered as a medicament. 



Much has been done to clear up this question by the employment of 

 microchemical tests to trace the course of iron through the intestine. 

 When mice are fed upon milk alone for a considerable period, on placing 

 the alimentary canal of these animals in ammonia and ammonium sul- 

 phide the characteristic precipitate of iron sulphide does not appear, 

 or at the most there is only a very slight green coloration. Now milk 

 is one of the articles of diet which is poorest in iron, cow's milk con- 

 taining only about 2.3 mg. of iron per 100 grammes of dry substance. 

 Very different results are obtained if the mice are fed upon milk to which 

 inorganic salts of iron have been added. In the stomach there is little 

 if any reaction for iron, while in the duodenum there is a marked green 

 coloration. If the tissues of the intestine are examined under the micro- 

 scope, little granules of iron are found imbedded in the protoplasm 

 of the intestinal epithelium, and leukocytes are found laden with 

 minute particles of iron. In the jejunum, however, and in the ileum, 

 very little iron is found, while in the cecum and large intestine a strong 

 iron-test is once more obtained. 



Coming from the intestinal canal, especially from the duodenum, 

 the lymphatics may be seen filled with cells containing iron. The liver 

 and spleen give much stronger tests for iron than those of the mice 

 fed upon milk alone. 



There can be no question, therefore, but that the inorganic iron- 

 salts thus administered are absorbed. Part of the iron appears to be 

 conducted by way of the lymphatics to the thoracic duct and the blood- 

 stream. Part is unquestionably conducted by the portal vein to the 

 liver, which is a storehouse of iron as it is of many other things . The 

 absorption takes place mainly in the duodenum; the excretion of waste 



