588 M. BIOT ON APPLYING CIRCULAR POLARIZATION TO THE 
formed is also found in it, the fermentation of which enfeebles the ro- 
tation without changing it. There is nothing [in its polarizing action ] 
which indicates the existence of cane or grape sugar. 
The nature therefore of these two sugars which are contained in the 
foliaceous parts of the plant become changed like that of gum, by tra- 
versing the collars of the ears; and they serve as materials to the young 
grain, by which they are formed into dextrine, and the other products 
which compose the perisperm. 
I have made analogous experiments upon the young shoots of wheat, 
but guided by the preceding, I have taken them more in division, ap- 
plying them separately to the various foliaceous organs which in the 
rye I had studied as a whole. In these organs I found diversities of 
composition, of which I had no suspicion. 
I commenced my experiments on the 19th of May, upon young shoots 
of wheat in which the ears were not yet developed. Suspecting that 
the composition of the leaves was different from that of the stem, and 
that they were destined to nourish it after fecundation, in the same 
manner as the leaves of trees nourish or form the new annual layer of 
bark and alburnum, I carefully detached the cylindrical stalk from the 
vaginating leaves which surround it, and treated these two parts sepa- 
rately by the processes which I have just described, viz. by water, alco- 
hol and fermentation. 
The stems, like those of the rye, presented three carbonated sub- 
stances, viz. grape sugar turning to the left, cane sugar turning to the 
right, and a substance turning to the left which may be precipitated 
by alcohol. The relative proportions of these three principles varied 
considerably with the progress of vegetation. On the 20th of May their 
mixture produced a resultant of rotation directed towards the right, 
showing that cane sugar was predominant in it; but on the 4th of 
June, the ears having left the stems and flowered, the resultant of the 
stems had passed to the left, and was afterwards constantly maintained 
in that direction, evincing that the cane sugar had become relatively 
less abundant. It will presently be shown that in the ears it had passed 
in excess. 
The leaves furnished results very different from those of the stems ; 
they contained indeed a mixture of grape and cane sugar and a sub- 
stance precipitable by alcohol and soluble in water after that precipita- 
tion, but, contrary to the stems, the proportion of cane sugar consider- 
ably exceeded that of grape sugar; besides, the precipitable matter 
having exerted a rotation to the right seemed to be dextrine, while in 
the stems the precipitable substance had a rotation to the left, and ap- 
peared by this character analogous to gum. 
The leaves preserve this state of composition as long as their vitality 
continues, but when fecundation is effected they may be seen gradually 
