544 
L. H. FKIEDBURG. 
not assimilated. However, he faced the fact, as well as every 
one of us, that some of these substances were of a certain 
beneficial result. This he explained then as consisting in an 
entirely secondary mode of action. An action of the iron 
upon the intestinal gases, mainly upon hydric sulfid, with 
which the iron would combine, forming black ferrous sulfid, 
eliminating it as one of the poisonous intestinal gases and ren¬ 
dering its action upon the iron contained in the blood impos¬ 
sible. Also a mucin-iron would be formed. 
But then Robert did not rest there. He found that the 
chicken was able to produce its haemoglobin, embryonically 
and post embryonically, from yolk of egg. Experiments with 
this substance upon carnivora, including man, were not en¬ 
couraging, since yolks are not compatible in large amounts. 
On the other hand he found that the dog, which scarcely 
can be said to feed upon yolks, covers the entire metabolic 
loss of iron by the blood which he partakes of in his food. 
The blood is therefore to be considered the true starting 
point for the correct administration of iron to be assimilated. 
Now, all the blood iron preparations existing heretofore had 
two drawbacks. They consisted either of pure dried blood, i 
which is objectionable from two points of view: first, from 
that of taste; second, by the fact that it covers the intestinal 
canal with a black tarry mass. Or such blood was mixed 
with iron salts which as such had no value other than that of 
neutralizing H 2 S, but which eventually produced impaired 
digestion, if not worse than that, metal kidney, after pro¬ 
longed use. Nevertheless, the dog stood there as a living 
example of a carnivora partaking successfully of blood. 
Now Robert reasoned thus: If for the human system the 
dog cannot appear as a prototype, what could be abstracted 
or learned from this example concerning man? What is the 
fate of blood partaken of as a food ? The action of the intes¬ 
tinal tract upon such substances as blood is a reducing one. 
The word reducing is to be understood in a chemical sense. 
It had therefore to be tried what effect reducing substances 
would have upon the blood, extra corpus, and then if such 
action was discernible how would the products obtained act 
after internal administration. 
