2OO Natural .Theology. 



rainless islands of South America that we find 

 guano, a compound rich in nitrogen ; and in similar 

 places, in caves, and beneath old buildings, we find 

 an accumulation of nitrates. 



We have no direct evidence, then, of the presence 

 of nitrogen on our globe in its earliest history. It 

 is only when we find the remains of organic beings, 

 that we have data for inferring its existence. It 

 may have been brought into its place among the 

 elements that compose our globe, after oxygen had 

 struggled with the other elements, and changed 

 them by its Titanic grasp into the materials that have 

 hardened into stone. Certain it is, however, that 

 nitrogen is essential to all the higher organisms. 



It is the nitrogen compounds of plants that chiefly 

 form the food that builds up the animal body and 

 supplies its waste. For this purpose it is well fitted 

 by its weak chemical affinity, and the nature of its 

 compounds. It is easily broken up in every combi- 

 nation, and the resulting compounds being soluble 

 are most readily eliminated from the system. Its 

 compounds naturally formed by decomposition are 

 volatile, and thus being disseminated by the law of 

 diffusion in the air, are ever present, to be washed 

 down by the falling waters for the nourishment of 

 plants. And small quantities of its compounds are 

 undoubtedly formed by the action of electricity and 

 other agencies in the atmosphere itself, so that this 

 inert element is slowly but surely brought under the 

 power of plant life, and through plants it takes its 

 appointed place in the highest organic forms. 



