usual form. The colorless corpuscles are larger than the red and differ
from them in being extremely irregular in their shape, and in their
tendency to adhere to a smooth surface, while the red corpuscles float
about and tumble over one another. They are chiefly remarkable for their
continual variation in form. The shape of the red corpuscles is only
altered by external influences, but the white are constantly undergoing
alterations, the result of changes taking place within their own
substance. When diluted with water and placed under the microscope they
are found to consist of a spheroidal sac, containing a clear or granular
fluid and a spheroidal vesicle, which is termed the _nucleus_. They have
been regarded by some physiologists as identical with those of the lymph
and chyle. Dr. Carpenter believes that the function of these cells is to
convert albumen into fibrin, by the simple process of cell-growth. It is
generally believed that the red corpuscles are derived in some way from
the colorless. It is supposed that the red corpuscle is merely the
nucleus of a colorless corpuscle enlarged, flattened, colored and
liberated by the bursting of the wall of its cell. When blood is taken
from an artery and allowed to remain at rest, it separates into two
parts: a solid mass, called the clot, largely composed of fibrin; and a
fluid known as the _serum_, in which the clot is suspended. This process
is termed _coagulation_. The serum, mostly composed of _albumen_, is a
transparent, straw-colored fluid, having the odor and taste of blood.
The whole quantity of blood in the body is estimated on an average to be
about one-ninth of its entire weight. The distinctions between the
arterial and the venous blood are marked, since in the arterial system
the blood is uniformly bright red, and in the venous of a very dark red
color The blood-corpuscles contain both oxygen and carbonic acid in
solution. When carbonic acid predominates, the blood is dark red; when
oxygen, scarlet. In the lungs, the corpuscles give up carbonic acid, and
absorb a fresh supply of oxygen, while in the general circulation the