186 INORGANIC AGENTS 



theory, now generally accepted, holds that the iron absorbed 

 into the blood is only that contained as a constituent of the 

 nucleoalbumins occurring naturally in animal or vegetable 

 foods. A larger part of this natural source of iron is ordi- 

 narily transformed — as is all that given as medicine — into 

 the insoluble sulphide in the intestines. When iron is 

 deficient in the blood, as in ausemia, iron is only of value 

 therapeutically by uniting with sulphur compounds of the 

 food or those formed as products of indigestion, thus enabling 

 the iron in the food to become absorbed by protecting it 

 from decomposition and transformation into the insoluble 

 sulphide. The action of iron is thus indirect. 



The older hypothesis taught that iron is absorbed as an 

 albuminate of iron and sodium, or is converted into that 

 combination in the blood. No theory, however, can 

 invalidate the fact that iron and its salts are beneficial in 

 anaemic states by improving the quality Oi the blood, 

 nutrition and general health. 



Blood. — In anaemia, iron indirectly increases the amount 

 of haemoglobin in the blood, and also the number of red 

 corpuscles. The latter effect is not so marked as with 

 arsenic. In regard to iron increasing the number of corpus- 

 cles, we may say that the blood-forming organs are stimu- 

 lated, or supplied- with blood-making material by iron. 

 Iron increases the power of the red corpuscles to hold 

 and carry oxygen from the lungs to the tissues, and to 

 transform it into ozone. Iron is then indirectly an oxidizing 

 agent, stimulating tissue change and vital activity. On 

 account of the astringent properties of iron, when applied 

 externally to the tissues, it is thought that its tonic action 

 internally depends, in part, upon its stimulating the con- 

 tractility of the muscles and vessels, and, therefore, improv- 

 ing tone. 



Elimination. — Although, as we have seen, the iron given 

 as medicine to animals is excreted unabsorbed, yet iron is 

 eliminated to a slight extent by the urine, bile, saliva, sweat 

 and tears. 



