DESIGN IN NATURE 281 



its waters might have been alkaline and its surface an 

 alkaline waste. 



If chlorine were as abundant as oxygen, then the 

 air would be laden with a deadly gas; or if bromine 

 were as abundant, the streams on the surface of the 

 earth would be liquid poison. 



The various poisonous elements exist in such small 

 quantities that they are all locked up in harmless and 

 useful compounds. Many of the most useful com- 

 pounds contain elements which, in the uncombined 

 condition, would be destructive to life. Common 

 salt, for example, is composed of two deadly ele- 

 ments. 



Again, it was necessary in order to form stable con- 

 tinents that would remain permanently above the 

 water of the oceans, that most of the minerals on 

 the surface of the earth should be quite insoluble in 

 water, otherwise the land would soon be carried in 

 solution into the oceans. This object has been well 

 accomplished by the great abundance of especially a 

 few elements, such as silicon, aluminum, calcium, 

 magnesium, iron, carbon, oxygen and others, which 

 form harmless, insoluble compounds, and which are 

 adapted, not only to give permanence to the conti- 

 nents, but also to form proper soils for the growth of 

 plants. 



I might continue indefinitely with regard to the 

 kinds and relative quantities of elements in the earth 

 as related to the existence and welfare of plants, 

 animals and man. The number of relative quantities 

 in which the seventy known elements might exist so 

 as to render life impossible is inconceivably great, 

 and when we add to this the probability that some 

 one or more of the various elements necessary to life 

 would, if left to chance to select, have been omitted, 

 it amounts, I think, to a certainty that the creation of 



