ON INCREMENT OF ANIMAL HEAT. 
423 
rature of the different parts of the body is, with one exception 
which I shall name specially, very equal. I have had the 
thermometer in every important structure within five minutes 
after death from increment of animal heat, and have watched 
the rate of cooling for an hour to find a perfect equality of 
temperature in all parts save one. In the bodies of the large 
muscles, in the intestines, in the blood, in the heart, in the 
structure of the lungs, in the liver, in the spleen, in the 
kidney, the distribution of heat is the same, and the rate of 
cooling, the conditions of exposure being alike, is the same. 
But there is one exceptional fact, and I must refer to it 
with equal earnestness and caution. It is this fact—that if 
immediately after death the bulb of a fine thermometer be 
plunged into the cavities of the trunk of the body, or into 
the vascular organs, or into the muscles, and at the same 
moment another thermometer (which has been tested and 
found to work uniformly with the thermometer employed for 
the trunk of the body)—if the bulb of this second thermo¬ 
meter, I say, be plunged into the centre of the brain, there 
will be found a difference of temperature in the brain from 
that which is found elsewhere. The temperature of the brain 
is lower than that of any other part of the body. The brain 
may be found even five degrees lower in temperature than 
the other parts; and I have many times, by exchanging 
thermometers—by taking one thermometer out of the brain 
and putting it into the place occupied by another thermometer 
in the centre of the pectoral muscle—seen the thermometer 
in the brain fall and the thermometer in the muscle rise. 
Nay, I have raised the mercury of a thermometer at one 
moment by plunging the bulb of the instrument into muscle, 
and have brought down the mercury at once by removing 
the instrument from the muscle, and plunging it into the 
substance of the brain. 
This fact is, to my mind, very singular. It may point to 
some unknown physiological law, or it may mean nothing 
but quick cooling from ready radiation. Yet the brain is 
not exposed, for the instant the drill has made entrance 
through the skull, the bulb of the thermometer fills the place 
which the drill occupied, and if there be more rapid radiation 
of heat from the brain than from the trunk, owing to the 
difference of mass (a view which our friend. Dr. Sedgwick, 
who has watched this experiment with me, maintains), even 
then the fact is of value, because what occurs after death 
will also occur during life, and the practical result will be 
that the brain of an animal living in an atmosphere below 
the temperature of its own body, wall have a lower tempera- 
