^mmmm^^m^ 



50 OF CARBON. 



with a view to prove that carbon did not form 

 the pabulum of plants. The circumstances 

 also under which plants yield carbon to the 

 atmosphere instead of absorbing it, must be 

 explained, and in doing so, a very nice, but at 

 the same time a perfectly clear and lucid dis- 

 tinction between the chemical transformations 

 and mechanical operations carried on by plants 

 will have to be considered. 



With a view to determine whether carbon 

 actually formed the principal nutrition of vege- 

 table life, seeds have been planted in fine mar- 

 ble reduced to powder, and in flowers of sul- 

 phur, and watered with water containing 

 carbonic acid gas in solution. Under these 

 circumstances, the seeds have generated and 

 lived to produce two or three leaves, but never 

 more, and in all cases the plant has then died : 

 and such experiments as these have been ad- 

 duced as conclusive evidence that carbon does 

 not form the nutriment of plants; but the par- 

 ties making these experiments have either been 

 willingly or culpably negligent in arriving at 

 this conclusion from such data. 



It will be seen as we proceed that many con- 

 ditions are necessary for the life and develop- 

 ment of the organs of plants, and that it is not 

 enough that one element forming it is admitted, 

 the principal nutriment should be present, but 

 the combined action of all is necessary. 



The organs of plants as well as of animals, 

 consist of a variety of substances, some re- 

 quiring carbon, others nitrogen, others again 

 hydrogen, and all the presence of metallic ox- 



