THE PHYSICAL BASIS OF LIFE 179 



oxygen and hydrogen combined. A considerable 

 proportion of the air and of the crust of the earth 

 is oxygen. Carbonic acid gas is belched by 

 volcanoes and expired by plants, and bubbles in 

 many mineral springs. There are thousands of tons 

 of nitrogen in the air. Accordingly, the elements 

 of life are plentiful and ready to hand. 



The abundance and availability of the atoms 

 that go to make protoplasm is a matter of much 

 importance, which has been usually quite over- 

 looked. Suppose gold had been an element 

 necessary for the manufacture of protoplasm, 

 where should we be ? Suppose carbon had been 

 utilisable only in its diamond form, how extensive 

 would the fauna and the flora of the globe be } 

 The universality and abundance of life is a matter 

 of the universality and abundance of the elements 

 that enter into its physical basis, and it is very 

 remarkable that the seething turmoil of the 

 cauldron of the molten world should have resulted 

 in the emergence and emancipation of the very 

 elements which protoplasm requires. It is very 

 amazing that the steam of the stewpan, that the re- 

 sidual atmosphere, and that the breath of volcanoes 

 should go to the making of microbes and men. 

 By what calculation were the atoms so arranged as 

 to have such a miracle-working remainder — such a 

 magic scum, such a fairy film } Who can say ! 



