J 50 French National Instihite. 



©bjections, and has intermixed several important facts con- 

 nected with the physics oF vegetables, and of an interest in- 

 dependent of the principal object. Of this number is the 

 germination of the tree called lecijthis by Linnaeus : although 

 belonging to the dicotyledons, the evolution of its seed is 

 not similar to any of the three modes hitherto adopted. Its 

 cotyledon is internal, and serves as a basis to the marrow, 

 which, in the opinion of M. Dupetit Thouars, is a proof in 

 favour of his ideas. 



The origin of carbon in plants is one of the most impor- 

 tant questions connected with vegetable oeconomy. The class 

 a few years ago made it the subject of a prize question with- 

 out obtaining a satisfactory answer : but the excellent work 

 published since by De Saussure, added to preceding labours 

 of M. Sennebier, has begun to throw great light on this ob- 

 scure subject. The decomposition of the carbonic acid is 

 displayed amid many complicated transformations, as the 

 chief and predominating act of vegetation, and as the pri- 

 mitive source of vegetable carbon. 



M. de Crell, a celebrated chemist residing at Helmstadt, 

 has this year communicated to the class some experiments 

 which afford a most exalted idea of the power of vegetation : 

 he informs us that he has raised plants in pure sand, so as- 

 to bear fruit: they were watered with distilled water only, 

 and supplied with a determinate quantity of air, in which 

 the carbonic acid must have been almost null, compared to 

 the quantity of carbon produced. Vegetables must therefore 

 have, according to M. Crell, the power of composing car- 

 bon, employing for this purpose only water, atmospheric 

 air, and light. This would be one of the greatest discoveries 

 in chemistry; but unfortunately this respectable chemist-has 

 not taken the necessary precautions for demonstrating his 

 assertion with the precision requisite on such an important 

 occasion: even when he covered his plants with a bell-glass, 

 it was out of his power to prevent the access of the external 

 air through the sand on which the bell-glass rested ; and as 

 the external air is continually in motion, it is very difficult to 

 estimate the quantity of carbonic acid which it can furnish, 

 Chemisxjiy. — Messrs. Fourcroy and Vauqutlin continue 

 with unabated ardour their Analyses of the Productions of 

 organised Bodies, and their remarks on the transformation** 

 wliich these productions are capable of undergoing: by these 

 labours they have established relations of the utmost impor- 

 tance between chemistry and physiology, and have thrown 

 a great deal oi light on the latter. 



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