he
thermometer in the shade generally stands at 108 degrees, without any
fatal effects to men or animals. The Russians often live in places
heated by stoves to 108 degrees or 109 degrees, and some philosophers
in this country, by way of experiment, remained a considerable time
in a room heated above the boiling point of water.

On the other hand, an equal excess of cold seems to have no greater
effect in altering the degree of heat proper to animal bodies.
Delisle has observed a cold in Siberia 70 degrees below the zero of
Fahrenheit's scale, notwithstanding which animals lived. Gmelin has
seen the inhabitants of Jeniseisk under the 58th degree of northern
latitude, sustaining a degree of cold, which in January became so
severe, that the spirit in the thermometer was 126 degrees below the
freezing point. Professor Pallas in Siberia, and our countrymen at
Hudson's Bay, have experienced a degree of cold almost equal to this.
All these facts tend to prove, that the heat of animals continues
without alteration in very different temperatures. Hence it is
evident that they must be able to produce a greater degree of heat,
when surrounded by a cold medium; and on the contrary, that they must
effect a diminution of the heat, when the surrounding medium is very
hot.

All these circumstances may be accounted for, by the principles we
have laid down; the decomposition of oxygen in the lungs.

There have not been wanting, however, some very eminent
physiologists, who have contended that animal heat is produced
chiefly by the nerves. They have brought forward in proof of this the
well known fact, that when the spinal marrow is injured, the
temperature of the body generally becomes diminished; and that in a
paralytic limb the heat is less than ordinary, though the strength
and velocity of the pulse remain the same. These facts, and others of
a similar nature, have induced them to believe, that the nervous
system is the chief cause and essential organ of heat; and they have
adduced similar arguments, to prove that nutrition is performed by
the nerves, for a limb which is paralytic from an injury of the
nerves, wastes, though the circulation continues. The truth is, that
the nerves exert their influence upon these, and all other functions
of the body, and modify their action. The liver secretes bile, but if
the nerves leading to it be destroyed, the secretion of bile will
cease; but who will say, that the bile is secreted by the ne