APPLICATIONS OF THE VISCOMETRIC METHOD 285

is increased. All liquids in the body, whether circulating or not
have the minimum viscosity compatible with their colloidal
content.

Oxygenated blood according to Haro (1876) is much more
fluid than blood through which carbon dioxide has been made to
bubble, the ratio between them being 5.61 to 6.08. Mere phys-
ical solutions of small amounts of gases in liquids usually affect
the fluidity but imperceptibly, but the data on this subject needs
amplification. Ether and ethyl alcohol added to the blood
increase its fluidity, whereas chloroform has the opposite
effect.

Poiseuille compared the rates of flow of blood serum through
glass tubes and through a given vascular territory varying the
viscosity of the serum by various additions. From the correla-
tion it has been assumed that the laws of Poiseuille apply to the
flow of blood through the capillaries of the body. Ewald (1877)
has questioned this conclusion and Huebner (1905) has noted an
incongruity in the rate of flow of solutions of known viscosity in
the organs of a frog. When blood flows through the capillaries
the corpuscles are deformed and the capillaries are more or less
elastic. The problems connected with the viscosity of the blood
are complicated by the fact that the fibrinogen of the blood in
contact with foreign substances produces coagulation which may
produce a coating on the inside of the tubes. Lewy (1897) how-
ever has found that Poiseuille's law holds good so long as no sedi-
mentation takes place, hence the more viscous the blood the
longer it will take to diffuse through a given vascular territory.
Burton-Opitz (1914) found that fasting produced a pronounced
increase in the fluidity of the blood of a dog. A meat diet has
the greatest effect in lowering the fluidity, a fat diet next, and a
diet of carbohydrates least of all. The fluidity of the serum
varies in a manner similar to that of the blood in these particular
experiments.

Bleeding a dog causes the fluidity of the blood to decrease.
When a dog was kept in a bath at 43°C the fluidity of the blood
increased, and it decreased when the temperature of the bath was
lowered to 23°, the most rapid change taking place in from 5 to
15 minutes according to Huerthle (1900).

According to Huebner the red blood corpuscles account for