WAVES OF HEAT AND WAVES OF DEATH. 
185 
new or extra labour to meet emergencies ; so much waste force 
enables the body to resist the external vicissitudes without 
trenching on the force that is always wanted to keep the heart 
pulsating^ the chest heaving_, the glands secreting or excreting, 
the digestive apparatus moving, and the brain thinking or 
receiving. 
Let us, even in the prime of manhood, disturb this distribu- 
tion of force ever so little, and straightway our life, which is 
the resultant of force, is disturbed. If we use the active force 
too long, we become exhausted, and call on the reserve ; if 
we continue the process, the result is failure more or less 
perfect, sleep, and, in the end, the last long sleep ; let us, 
instead of exhausting the force, cut it off at the sources where 
it is generated ; let us remove the carbon or coal that should 
go in as fuel-food, and we create prostration, and in con- 
tinuance a waning animal fire, sleep, and death; or let us, 
instead of removing or withdrawing the supply of fuel, cut off 
the supply of air, as by immersion of the body in water, or by 
making it breathe a vapour that stops the combination of 
oxygen with carbon, — such a vapour as chloroform, — and again 
we produce at once prostration, sleep, or death, according to 
the extent to which we have conducted the process. Lastly, 
if instead of using up unduly the active and reserve force, or 
instead of suppressing the evolution of force by the withdrawal 
of its sources, we expose the body to such an external tempera- 
ture, that it is robbed of its heat faster than it can generate it ; 
— if, that is to say, to supply, the waste heat, we draw upon the 
active and reserve forces, we call forth immediately the same 
condition as followed from extreme over- exertion, or from sup- 
pression of the development of force : we call forth exhaus- 
tion and sleep, and, in extreme case, death. 
We have had in our mind^s eye, in the above description, a 
man in the prime of life, in the centre of growth, and decay. 
In regard to the force of animation in him, we may look at 
him now retrospectively and prospectively. In his past his has 
been a growing developing body, and in the course of develop- 
ment he has produced an excess of force commensurate with 
the demands of his growth ; this enables him to bear a cer- 
tain excess of fatigue and exposure, without exhaustion and 
even with ease, until he has reached his maximum. When he 
stops in development, wLen he stands on a fair level with the 
external forces that are opposed to him, then his own force, 
for a short time balanced, soon sinks to be second in command. 
He feels cold more tenderly ; if his rest be broken the demand 
for artificial heat is urgent ; if he lose or njiss food, he fails 
quickly ; and, returning to our facts, as to the influence of the 
external temperature on mortality, these are the reasons why a 
