THE BEGINNINGS OF LIFE. 135 



atmosphere on fire with lightnings, from the bosom of 

 the tempest, that the second and scarcely less indis- 

 pensable aliment of plants, nitrate of ammonia, is 

 showered down for their behoof/ Thus the air is the 

 great storehouse for the pabulum of plants, so that, look- 

 ing at the subject, as M. Dumas says, ' from the loftiest 

 point of view, and in connection with the physics of 

 the globe, it would be imperative on us to say that, in 

 so far as their truly organic elements are concerned, 

 plants and animals are the offspring of the air.' 



It might be thought that plants derive the principal 

 part of the ingredients with which they build up their 

 own structures from the soil; but the experiments of 

 M. Boussingault have long since disproved this formerly 

 favoured assumption. He found that peas sown in 

 pure sand, moistened with distilled water, and fed by 

 the air alone, nevertheless found in this air all the car- 

 bon necessary for their development, flowering, and 

 fructification. Carbon is the most fundamental ingre- 

 dient of the vegetable kingdom ; all plants fix this 

 substance, and all obtain it from carbonic acid either 

 abstracting it directly from the air by their leaves, or 

 obtaining it through their rootlets. In the latter case 

 they may obtain it from rains which have fallen to the 

 earth impregnated with the carbonic acid of the atmo- 

 sphere, or else they procure it from that which is 

 liberated by the gradual decomposition of organic par- 

 ticles in the soil. But that the air is the great storehouse 

 whence, either mediately or immediately, plants procure 



