M. BIOT'S ANALYSIS OF THE VEGETATION OF THE GRAMINEX. 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 definitively chemistry and chemistry 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- 
ready enabled me to discover the singular modifications that the foli- 
aceous organs of exogenous trees produce in the ascending sap which 
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 phenomena of their 
vitality. The trunks of the Gramineae, the existence of which is com- 
pleted in a year, presents in this narrow circle the whole series of the 
analogous phenomena. From this class I have selected rye 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 féculasés) 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 roots are 
developed. But 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 
