M. Dumas on the Chemical Statics of Organized Beings. -i57 



But what can be clearer and more conclusive than the 

 experiment of M. Boussingault, in which peas, sowed in 

 sand, watered with distilled water, and having no aliment but 

 air, have found in that air all the carbon necessary for deve- 

 lopment, flowering and fructification ? 



All plants fix carbon, all borrow it from carbonic acid, 

 whether this be taken directly from the air by the leaves, 

 whether the roots imbibe within the ground the rain water 

 impregnated with carbonic acid, — or whether the manures, 

 whilst decomposing in the soil, supply carbonic acid, which 

 the roots also take possession of to transmit it to the leaves. 



All these results may be proved without difficulty. M. 

 Boussingault observed that vine leaves which were inclosed 

 in a globe, took all the carbonic acid from the air directed 

 across the vessel, however rapid the current. M. Boucherie 

 also observed enormous quantities of carbonic acid escape 

 from the divided trunk of trees in full sap, evidently drawn by 

 the roots from the soil. 



But if the roots imbibe this carbonic acid within the earth, 

 if this passes into the stalk and from thence into the leaves, it 

 ends by being exhaled into the atmosphere, without alteration, 

 when no new force intervenes. 



Such is the case with plants vegetating in the shade or at 

 night. The carbonic acid of the earth filters through their 

 tissues and diffuses itself in the air. We say that plants pro- 

 duce carbonic acid during the night; we should say, in such 

 a case, that plants transmit the carbonic acid borrowed from 

 the soil. 



But let this carbonic acid, proceeding from the soil or taken 

 from the atmosphere, come into contact with the leaves or the 

 green parts, and let the solar light moreover intervene, then 

 the scene all at once changes. 



The carbonic acid disappears ; bubbles of free oxygen arise 

 on all the parts of the leaf, and the carbon fixes itself in the 

 tissues of the plant. 



It is a circumstance well worthy of interest, that these green 

 parts of plants, the only ones which up to this time manifest 

 this admirable phaenomenon of the decomposition of carbonic 

 acid, are also endowed with another property not less pecu- 

 liar, or less mysterious. 



In fact, if their image were to be transferred into the ap- 

 paratus of M. Daguerre, these green parts are not found to be 

 reproduced there ; as if all the chemical rays, essential to the 

 Daguerrian phenomena, had disappeared in the leaf, absorbed 

 and retained by it. 



The chemical rays of light disappear, therefore, entirely in 



