HOW THE BODY FIGHTS DISEASE 



complexity in the materials of which these are com- 

 posed. The development of organic chemistry has 

 revealed precisely the opposite. The world of the 

 non-living is made up of a rather large variety of 

 elements, put together for the most part in a very 

 simple way ; the world of living things, on the con- 

 trary, seems composed of a very few elementary 

 substances, put together in a most intricate way. 

 A little carbonic acid, water, ammonia, oxygen, a 

 trace of some mineral salts, and perhaps a dash of 

 sulphur and phosphorus, and you have the physical 

 bases of life. Such varied articles as the white of 

 an egg, cheese, or lean beefsteak hardly differ at 

 all in their constituents ; it is simply a question of 

 chemical structure, or, as one might say, architect- 

 ure. 



After this one will not be surprised to learn that 

 many of the organic poisons that is to say, the 

 poisons elaborated by the living organism differ 

 so slightly from the ordinary foods of the body as 

 to have for a long time baffled the chemist in his ef- 

 forts towards a satisfactory analysis. They are in 

 many instances substances made up not merely of 

 identically the same elements, but incidentally in 

 the same proportions. In more technical language, 

 they are what the chemists call isomeres i. e., 

 made out of the same parts. Their differing physi- 

 ological and chemical reactions, therefore, may be 



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