98 THE HUMAN BODY. 



any reserve of nutritious matter which may have been 

 stored up in it when the starvation commenced, and as 

 this is expended it becomes weaker and weaker until 

 death supervenes. * 



How long a man, totally deprived of food, can keep 

 alive, will depend, partly, on how much reserve material, 

 capable of oxidation, he has stored up in him when the 

 starvation period commences ; but largely, also, on the ex- 

 tent to which he can spare himself muscular work and 

 loss of heat. The breathing movements and beat of the 

 heart must go on, but if the individual lies quiet in bed 

 he need do little or no other muscular work ; and if he is 

 well covered up with blankets, the loss of heat from the 

 body is slight and calls for but little oxidation of the tissues 

 to compensate for it.f Also, a fat person will survive starva- 

 tion longer than a lean one ; during the process his fat is 

 slowly burnt; but so long as it lasts he can supply his mus- 

 cles with something which can be oxidized to yield working 

 power, and he also, by its burning, can maintain his tem- 

 perature. Fat is, in fact, a sort of reserve fuel, laid up in 

 the body, and a man, in the strict sense of the word, can 

 hardly be said to begin to starve until his fat has nearly all 

 been used up.J 



Upon what does the length of life of a man getting no food de- 

 pend? What expenditures of energy must go on all the time? How 

 does lying in bed diminish the expenditure of energy? Why will a 

 fat man deprived of food live longer than a lean one? 



When does a fasting man really begin to starve? 



* When warm-blooded animals are starved their temperature slowly falls; and 

 when it conies down to about 77 p. (25 c.) death occurs: the various tissues at 

 that temperature can no longer work so as to maintain life. 



t Hence Dr. Tanner, and "fasting girls" keep in bed, warmly covered up, 

 most of the time: the losses of the body in mechanical work and heat are thus 

 reduced to a minimum, and consequently the oxidation of the food reserves stored 

 in the body at the beginning of the fast. 



t Some warm-blooded animals, as bears, hibernate; that is, sleep all through 



