42 OF THE ASSIMILATION OF CARBON. 



supported by a single piece of its foundation ? 

 Assuredly not. Yet the strongest proof would have 

 been given, that each portion of the pedestal could 

 be removed without the downfall of the column. 



Animal and vegetable physiologists, however, 

 come to such conclusions with respect to the pro- 

 cess of assimilation. They institute experiments 

 without being acquainted with the circumstances 

 necessary for the continuance of life with the 

 qualities and proper nutriment of the animal or 

 plant on which they operate or with the nature 

 and chemical constitution of its organs. These 

 experiments are considered by them as convinc- 

 ing proofs, whilst they are fitted only to awaken 

 pity. 



Is it possible to bring a plant to maturity by 

 means of carbonic acid and water, without the aid 

 of some substance containing nitrogen, which is an 

 essential constituent of the sap, and indispensable 

 for its production ? Must the plant not die, how- 

 ever abundant the supply of carbonic acid may be, 

 as soon as the first small leaves have exhausted 

 the nitrogen contained in the seeds ? 



Can a plant be expected to grow in Carrara 

 marble, even when an azotized substance is supplied 

 to it, but when the marble is sprinkled with an 

 aqueous solution of carbonic acid, which dissolves 

 the lime and forms super carbonate of lime ? A 

 plant of the family of the Plumbaginece, upon the 

 leaves of which fine hornlike, or scaly processes of 



