610 MAN AS A CONQUEROR 



means leadership, then it should mean healthy leadership in the 

 best sense. 



The human body has been likened to an engine by many writers. 

 It requires fuel and oxygen in order to release energy, forms wastes 

 which have to be eliminated, and must have frequent rest in order to 

 do its work most efficiently. Both machine and body eventually 

 wear out, but we do not refer to a sick machine although we do speak 

 of a sick person. Anyone may abuse his body through lack of sleep, 

 exercise, or improper food so that it will not function properly. He 

 may poison it with alcohol and nicotine and injure some of the internal 

 organs so that they never will have their former efficiency. He may 

 meet with an accident and be crippled, or he may be attacked by 

 microscopic foes such as bacteria or protozoa and thus suffer from 

 disease. Not only in these respects does the body differ from the 

 machine, but also for the reason that it can repair itself, a thing which 

 no machine can do. When it is in perfect condition it is called a 

 healthy body. 



What Is the Biological Significance of Death? 



In old age, the body machinery begins to wear out, the normal 

 functions slow down, tissues wear away, the liver, kidneys, reproduc- 

 tive and nervous tissues shrink and cease from more active function- 

 ing. Muscles lose their tone, the weight becomes less, special sense 

 organs lose their accuracy as the body reacts more slowly to stimuli 

 and the skin does not shrink as fast as do the tissues beneath. Diges- 

 tion does not function as well as formerly and apparently there comes 

 a slow poisoning of the tissues, since the cells give out wastes more 

 rapidly than they are eliminated. The body machine wears out 

 because it cannot eliminate the poison fast enough. At length some 

 part of the system gives out. In most cases the muscles of the 

 heart, that have been constantly at work since before birth, sud- 

 denly stop, or the arteries, which have become brittle through faulty 

 calcium metabolism, break and death ensues. 



We often think of an animal as dead if its head is cut off. But 

 under such circumstances the heart of a frog or a snake continues 

 beating. Obviously such an animal is not all dead. The work of 

 Carrel with excised tissues gives evidence that the individual cells of 

 the body, if in a favorable environment, will continue living perhaps 

 indefinitely. Physically, death means the breaking of the plasma 

 membranes of the cells so that their selectively permeable properties 



