X 
THE BEAR 
349 
procure. The body can exist for an incredible length 
of time, provided that it is capable of undisturbed 
rest, which appears in a certain degree to take the 
place of extraneous nutriment. It is well known 
that every exertion of the muscles is a loss of power, 
the force of the body being represented by heat. 
To lift a weight or to move a limb requires a certain 
expenditure of heat, which means force ; this loss of 
heat and power is recuperated by food ; thus in the 
absence of provisions for the necessary supply, there 
would be no loss of heat if there is no exertion. 
Sleep is the resource, as the body is not only at rest, 
but the brain is also tranquil; there is accordingly a 
minimum of exhaustion. Human beings have been 
known to live without food of any kind (excepting 
water) for a period of forty days, and have then 
resumed their ordinary course, simply confining 
themselves to moderate diet for the first few days 
after their long abstinence. In a time of starvation 
in Africa I have frequently composed myself to sleep 
in the absence of my daily food, and I have awoke 
without any disagreeable craving for a meal. 
Continued sleep will to a certain extent render the 
body independent of other nutriment, and I should 
imagine that the custom of hybernation has been 
induced by necessity. At a season when the fruits 
of the earth are exhausted, the ground frozen to 
a degree that would render scratching for roots 
impossible, an animal that was dependent upon such 
productions for its existence must either starve or 
sleep. The sleep is in itself a first stage of the 
