ITS SCOPE AND METHOD 63 



dioxide. Another is water. The large quantity of oxygen 

 in these end-products suggests the r61e oxygen is playing 

 in the decomposition of the living matter. 



The need for oxygen the oxygen hunger is acute 

 in ourselves and in all briskly living animals. Ten 

 minutes, even five, without oxygen and certain organs, 

 notably the brain, strike work entailing in sequence the 

 upset of other parts of all the linked machinery of the 

 living body. Breathing ceases, and slowly there follows 

 coldness, the absolutest sign of death. Oxygen being 

 excluded from its part, the normal chemical decomposi- 

 tion ceases ; and the complex material of the body will 

 fall a prey to forms of decomposition other than those 

 associated with life, though the end-products may be 

 ultimately the same. 



What, then, is the nature of this material that, give 

 it oxygen, so composes and decomposes as to mani- 

 fest the phenomena we sum as ' life ' ? Chemical physio- 

 logy reveals a thing unexpected to many, though a 

 fulfilment of much ancient figurative expression. Last 

 century the chemist performed a mighty analysis, 

 testing the nature of the materials of all the million-sided 

 universe perceptible to man. He learned that despite 

 all its diversity it is yet composed from relatively few 

 essential substances, therefore called elemental. This 

 analysis included living matter. It might have been 

 thought that the material basis of life would contain 

 elements peculiar to itself and different from those of 

 the inanimate world. It is not so. Some few o(,the 

 elements most widely spread in air and sea and rock 

 make up the tale of those which everywhere compose 

 the machinery of life in all its forms. The secret of 

 the chemical difference between life and death lies there- 

 fore less in the nature of its elemental ingredients than 



