208 PROPORTION OF RED CORPUSOLES. 
the Red Corpuscles draw into themselves nearly the whole 
of the iron, phosphorus, and potass, which the chyle pours 
into the circulating current; and that they modify a large pro- 
portion of the solid matter of the blood, that which they con- 
tain being notably different in composition from that of the 
liquor sanguinis, which does not differ, save in the proportion 
of its components, from the liquid portion of Chyle or Lymph. 
233. The proportion of Red Corpuscles to the whole mass 
of the blood varies greatly in different animals, and even in 
different states of the same animal. It is greatest in those 
which have the highest muscular vigour and activity, and 
which consume the largest quantity of oxygen by respiration ; 
hence these particles are rather more numerous in the blood 
of Birds than in that of Mammals, and far more abundant 
in these last than in Reptiles or Fishes, Again, they are 
more numerous in Men of ruddy complexion, strong pulse, 
and active habits, than in those of pale skins, languid cireu- 
lation, and comparatively feeble powers. In a healthy Man 
they seem to constitute about half the mass of the circulating 
blood ; but they contain as much as three-fourths of its solid 
matter, the proportion of dy corpuscles being betes 150 in 
1000 parts of blood, whilst that of the other solid matters 
is about 50. A very marked decrease occasionally presents 
itself in disease ; the proportion of dry corpuscles being some- 
times reduced as low as 27. When too abundant, they pro- 
duce what is known as the plethoric condition of the body, 
in which hemorrhage from the bursting of a blood-vessel is 
liable to occur. Their number is effectually reduced by bleed- 
ing ; and the aspect of those who have suffered from extreme 
loss of blood, gives sufficient evidence that the deficiency is 
not made-up for a long period. The most effectual means of 
restoration, in cases where the proportion of blood-corpuscles 
is too low, is a highly nutritious diet, with the administration 
of iron as a medicine ; for this substance seems to have the 
power of hastening the reproduction of the corpuscles, being 
itself an essential ingredient in their contents; and there 
are facts which show its remarkable power of increasing their 
amount in proportion to the mass of the blood. 
234. It appears that the red corpuscles, like other cells, 
have a certain allotted term of life; and as they are con- 
tirnually dying, they must be as continually reproduced. The 
