212 
THOMAS WALLEY. 
though its quantity in proportion to the other elements of the 
blood, it yet performs a most important function, viz., the carry¬ 
ing of oxygen to the tissues; the effects of the withdrawal or 
non-assimilation of iron are quickly seen in the pale color (pallor) 
of the visible mucous membranes—as of the eye, nose and mouth ; 
and in man, in the blanching of the skin. In all animals the 
effects of its loss are seen in the excessive rapidity of respiration 
for the purpose of compensating, by the quantity taken into the 
lungs, for the small quantity of oxygen which the blood cells are 
capable of carrying to the tissues. 
It is now demonstrated also that iron acts as a stimulant to 
the liver. 
An animal in whose body iron is deficient becomes compara¬ 
tively bloodless, though its carcass may be laden with fat; it is 
said to be anaemic , and if this condition is pushed too far it dies. 
Iron may exist in abundance, but by the influence of adverse 
agencies, such as the action of disease or disease germs, the red 
cells may be incapable of appropriating it; and thus, in the midst 
of plenty an animal may die of oxygen starvation. If iron is 
assimilated in superabundance, an opposite extreme is induced, 
viz., excess of blood (hypersemia), and inflammations may result. 
Not only phosphorus, but, as has recently been shown, a salt 
of potash (the chlorate) has the power of so changing the coloring 
matter of the blood as to render it useless and to cause it to be 
passed out by the kidneys, giving to the urine a peculiar but char¬ 
acteristic color. Carbonic acid renders the blood dark and dis¬ 
places oxygen. Carbonic oxide heightens the color but brings 
about such a change in the condition of the iron as effectually to 
prevent re-oxidation; hence the primary and secondary effects of 
exposure to the gases given off in combustion or fires and hence 
the blood-stained urine we sometimes see passed by animals which 
have been exposed to the influence of those gases in burning 
stables and cowsheds. 
Having described some of the characters of the blood, I will 
now consider the influence exerted upon it by the more important 
organs and functions of the body, viz., by digestion and assimila¬ 
tion, by oxidation and nutrition ; by the liver, the bowels, the 
