REMARKS ON COMPOSITION OF THE BLOOD. 
731 
is ‘ contained in their interior, and is designated hamatine. 
Mixed with this is another fluid, called glob aline, which is 
closely allied to albumen in its chemical composition. W ith 
the Juemato-globuline are found the salts of iron—to the extent 
of about 6 per cent.—proper to the blood ; so that the 
contents of the cells may be said to be very complex in their 
nature. 
The alteration of the colour of the blood was until lately 
believed to be due to a chemical change wrought in the iron 
of the Juemato-globuline by the successive influences of oxygen 
and carbonic acid—this existing in the form of ajt^r-oxide in 
arterial and a jpr^-oxide in venous blood. More recent in¬ 
vestigations have, however, disproved this, which is known as 
the Liebigian theory, by showing that when the haemato- 
globuline is liberated from the cells, it does not change its 
shades of hue by an exposure to the gases in question; and 
further, that after all the iron is removed, its red colour still 
remains. 
The absorption both of oxygen and carbonic acid by the 
blood is found to produce a physical change in the condition 
of the red cells. Thus bv the influence of the first-named, 
the cell-walls are contracted or shrivelled, while by the latter 
they are dilated or expanded. These alterations in form 
necessarily lead to an alteration in the refraction of the rays 
of light, and it is now- thought, that the bright-red colour of 
arterial and the dark hue of venous blood are mainly due to 
this simple cause. The action also of carbonic acid on the 
salts of blood contained within the serum is said to have an 
influence in producing the Modena-red colour. 
In concluding this part of our subject we may incidentally 
direct attention to the fact, that the inhalation of ether, chloro¬ 
form, and other similar anaesthetic agents produces a dark- 
coloured blood, which is found under such circumstances to 
be flowing, not merely through the veins, but the arteries also, 
and of necessity but imperfectly supporting the various 
functions of organization and life. 
We come now to speak of the only remaining constituent 
of the circulating fluid, which it is necessary to direct special 
attention to, namely — 
The White Corpuscles. —These bodies, although ex¬ 
ceedingly numerous, are considerably less so than the red. 
It has been computed that about one white to fifty red cells 
exists in a healthy state of the system, and in almost every 
other respect the w hite cells differ from the coloured. In size 
thev exceed them : for while the average dimension of the red 
cell is about the l-3500th of an inch, the white measures as 
