PHYSICAL AND CHEMICAL CHARACTERS. 329 



All we have to do is to restore to them an appropriate 

 ambient medium. The whole question is one of 

 knowing and being able to realize, for this or that 

 part which we wish to reanimate and to rejuvenate, 

 the very special or very delicate conditions that this 

 medium must fulfil. As we have said, success is 

 attained in this respect as far as the heart is con- 

 cerned, and this is why we are able to reanimate and 

 to" revive the heart of a dead man. It is hoped that 

 ideas along these lines will extend with the progress 

 of physiology. 



After this sketch of the conditions and of the 

 varieties of cellular death we must return to the 

 essential problem which is engaging the curiosity of 

 biologists and philosophers. Is death unavoidable, 

 inevitable? Is it the necessary consequence of life 

 itself, the inevitable issue, the inevitable end ? 



There are two ways of endeavouring to solve this 

 question of the inevitability of death. The first is to 

 examine popular observation, practised, so to speak, 

 unintelligently and without special precautions. The 

 second is to analyze everything we know relative to 

 the conditions of elementary life. 



