IRON IN THE LIVING BODY. 811 



not till 1864 that Hoppe-Seyler succeded in obtaining it pure and 

 crystallized. But Liebig had already perceived its essential proper- 

 ties, and was able to point out approximately its functions as early as 

 1845; yet the single fact that there was no assimilation possible be- 

 tween this substance and the salts of iron, cut this question off into 

 a kind of negative suspense. Different from these compounds, it 

 could not behave like them, and accomplish slow combustions of the 

 same type. It is a remarkable fact, and one that illustrates well how 

 iron preserves through all its vicissitudes some trace of its funda- 

 mental property of favoring the action of oxygen on substances, 

 that this composition, so special and so different from the salts of 

 iron, behaves nearly as they do. While it is not of itself an "ener- 

 getic combustible, it is, according to Liebig's expression, " a trans- 

 porter of oxygen " — a luminous view, which the future was destined 

 to confirm. Although the transportation is not produced by the 

 mechanism supposed by Liebig, but by another, the general result 

 is very much the same from the point of view of the physiology of 

 the blood. The coloring matter of the blood conveyed by the glob- 

 ules fixes oxygen in contact with the pulmonary air, and distributes 

 it as it passes through the capillaries upon the tissues. The globule 

 of blood brings nothing else and distributes nothing else, contrary 

 to the opinion that had been held before. The theory of slow com- 

 bustion effected through iron, while not absolutely contradicted in 

 principle, was not entirely confirmed in detail, so far as concerned 

 iron, or the more prominently ferruginous tissue. 



No search was made for other tissues or organs presenting more 

 favorable conditions, for no others were known that had iron in 

 themselves. The liver and the spleen were supposed to receive it 

 from the blood under the complicated form in which it exists there, 

 or under some equivalent form. It was not, therefore, supposed till 

 within a very few years that the two conditions were realized in any 

 organ that were required to secure a slow combustion by iron — 

 that is, combinations resembling ferrous and ferric salts with a weak 

 acid and a source of oxygen. The doubt has been resolved by 

 recent studies. The liver fulfils the requirement. It contains iron 

 existing under forms precisely comparable to the ferrous and ferric 

 compounds, and is washed by the blood which carries oxygen in a 

 state of simple solution in its plasma and of loose combination in its 

 globules. Thus all the conditions necessary for the production of 

 slow combustion are gathered here, and we can not doubt that it takes 

 place. A new function is therefore assigned to the liver, and it be- 

 comes one of the great furnaces of the organism. 



Compounds of iron are so abundant in the ground and the water 

 that we need not be surprised when we find them in various parts 



