of themselves tend either to produce
undue loss of force, or that tend to prevent the development of force
at its origin. Thus affections which are accompanied with exhaustive
loss of fluids from the body, such as diabetes, dropsies, and
haemorrhages, are of the first class; affections in which due supply of
air to the lungs is prevented are of the second class, especially
bronchitis, a disease so commonly assigned as the cause of the deaths
among the members of the aged and enfeebled population, that succeed
immediately on an extreme fall of the thermometer.

FALL OF TEMPERATURE--MODE OF ACTION.

In what has been written above I have stated simply and in open terms
the fact that the fall of temperature produces a specified series of
results, by reducing the force of the living organism, and disposing
it to die. We may from this point investigate, from a physiological
point of view, the mode by which the effect is produced in the
economy. How does the decline of temperature act? Is the process
simple or compound?

EXTRACTION OF HEAT.

The process is compound, and into it there enter three elements. In
the first place, the body is robbed rapidly of its waste force, and
the reserve and active elements of force are, consequently, called
upon to the depression of the organism altogether. This obtains
because the medium surrounding the body, the air, unless it be
artificially heated, removes from its contact with the body a larger
proportion of heat than can be spared; and it might be possible to
produce such an influence on the body by sudden extraction of its heat
as to destroy it at once by the mere act. If a man could be surrounded
with frozen mercury he would die instantaneously, as from shock, by
the immediate extraction of his heat. But in ordinary cases, and under
ordinary circumstances, the mere rapid extraction of waste heat is not
sufficient to account for all the mischief produced by a low
temperature; for by artificial warmth and non-conducting garments, we
counteract the influence, and that, too, in a manner which proves
pretty successful. We may, therefore, leave this element of extraction
of heat as a most important, but not as the sole, agent of evil.

SUPPRESSED OXIDATION.

The second element is the effect on the process of oxidation of blood
under the influence of cold. We all are aware that if a portion of
dead animal or vegetable matter be placed at a low temperature, it
keeps for a consid