134 THE BEGINNINGS OF LIFE. 



kingdom is nature's laboratory, within whose sacred 

 precincts dead brute matter is coerced into more 

 elevated and complex modes of being, and is made to 

 display those more subtle characteristics which we find 

 in living tissues. Using only the great forces of nature 

 availing themselves only of the subtle motions ema- 

 nating from the Sun under the names of heat, light, and 

 actinism plants compel carbonic acid to yield up its 

 carbon, water its hydrogen, and nitrate of ammonia its 

 nitrogen; and, at the same time, these separated 

 elements, with some of the retained oxygen x , are still 

 further forced by an accumulation of these mysterious 

 impacts to enter into combinations of a higher order. 



M. Dumas, speaking of the sources whence are de- 

 rived the ammonia and the nitric acid used as food 

 by plants, says : c They are, in fact, produced upon the 

 grand scale by the action of those magnificent electric 

 sparks which dart from the storm-cloud, and furrowing 

 vast fields of air, engender in their course the nitrate 

 of ammonia, which analysis discovers in the thunder 

 shower. . . . As it is from the mouths of volcanoes, 

 then, whose convulsions so often make the crust of our 

 globe to tremble, that the principal food of plants, car- 

 bonic acid, is incessantly poured out ; so is it from the 



1 Dumas says (' Lee. de Philosophic Chimique,' p. 100, Paris, 1837) : 

 ' These are the four bodies, in fact, which, becoming animated at the fire 

 of the sun, the true torch of Prometheus, approve themselves upon 

 the earth, the eternal agents of organization, of sensation, of motion, 

 and of thought.' 



