M. BIOT's analysis of the vegetation of the GKAMINEjE. 585 



he may be aware of their occurrence as soon as they take place ; and 

 lastly, by affording characters of the same order for distinguishing the 

 greater number of the organic products which he isolates. We do not 

 here pretend to supply chemical tests, but simply to illustrate in many 

 cases the convenience of their application, and to characterize imme- 

 diately the consequences resulting from them by sensible effects ; for 

 it is deiinitively chemistry and chemistrj' alone by which the products 

 can be isolated and resolved into their component parts. 



The employment of this method, as the Academy has seen, has al- 

 readj'^ enabled me to discover the singular modifications that the foli- 

 aceous organs of exogenous trees produce in the ascending sap Avhich 

 supplies them with nourishment in their first development ; and it 

 afterwards assisted me in distinguishing the elaborated products which 

 these same organs convey under the cortical layers to nourish, or even 

 perhaps to form the new cellular tissue. Persons conversant with the 

 study of vegetable physiology can alone give to these researches the 

 generality necessary for the deduction of its laws. All my ambition 

 has been to offer them an experimental method of tracing these myste- 

 rious operations. The results that I now offer to the Academy are 

 directed to the same end, and are intended to confirm those previously 

 obtained, while they at the same time render them complete. 



The long duration of exogenous trees is accompanied by a propor- 

 tionate retardation of the total development of the phaenomena of their 

 vitality. The trunks of the GraminecB, the existence of which is com- 

 pleted in a year, presents in this narrow circle the whole series of the 

 analogous phaenomena. From this class I have selected rj^e and wheat, 

 with the intention of examining the various phases of their vegetation. 



From the researches on germination of physiologists and chemists, 

 we have learned what takes place immediately after the birth of these 

 plants. The amylaceous globules {globules feculases) deposited in the 

 perisperm of the grain around the embryo are emptied, and the dex- 

 trine which they contain is converted into sugar, which serves as nou- 

 rishment to the young stem until its foliaceous organs and I'oots are 

 developed. Rut when this first supply of aliment is exhausted, the 

 young plant is left to procure such as will continue its development. 



Now the nature of these new alimentary products, the modifications 

 which they undergo in the various parts of the plant, and the manner 

 in which these various parts contribute successively or simultaneously 

 to nourish the seed, and to supply it with the substances of which it is 

 to be composed, by transmitting the new alimentary products to the 

 fecundated ovary, have not I believe been hitherto experimentally de- 

 termined. 



It is necessary here to distinguish the solid materials, the fixation of 

 which constitutes the skeleton of the plant, from the juices and soluble 



