ANALYSIS OF THE VEGETATION OF THE GRAMINEiE. 587 



strong rotation towards the left, thus detecting the mixture of grape 

 sugar, not solidified, with cane sugar, which mutually concealed each 

 other before the latter w as interverted. The substance exhibiting a ro- 

 tation to the left, and precipitable by alcohol, experienced also the alco- 

 holic fermentation by contact with yeast, this property being either 

 proper to it or arising from a small quantity of sugar which might have 

 been entangled with it in the precipitation. But the effect of the fer- 

 mentation was only to weaken the rotation, without altering its direction. 



Twelve days after, on the 15th of May, the ears being more deve- 

 loped, but still far from flowering, the stems again presented the 

 mixture of these three substances. But the proportion of cane sugar 

 was increased, for it determined the i-esultant of the rotation in its pro- 

 per direction, towards the right, before fermentation. Wlien this sugar 

 was destroyed in the extract by boiling it with sulphuric acid, the in- 

 fluence of this acid changed the direction of the rotation of the sub- 

 stance precipitable by alcohol, which passed from the left to the right. 

 This, as M. Persoz and myself have shown, is also a property of gum. 



The extract from the ears before flowering presented characters 

 very different from the extract from the stems. Neither cane nor grape 

 sugar was detected in it, but only sugar of starch (sticre de fecule), 

 which the fermentation enfeebled without changing. Alcohol also 

 produced a precipitate in it, but of a different quality to that of the 

 stems, for it was not soluble in water, or only so in a very small degree ; 

 and this precipitate viewed with the microscope appeared formed only 

 of shreds of cellular tissue and the remains of integuments similar to 

 those which cover the globules of starch, without any sensible mixture 

 of pulverulent matter. These results agreed with M. Raspail's observa- 

 tions, that the pericarp of the Cerealia before fecundation is filled with 

 starch {fecule) in very small grains, the soluble matter of which is pro- 

 gressively absorljed by the ovary, and serves as nourishment to it when 

 the fecundation is effected. But as the extract of the eai-s made pre- 

 viously to fecundation here presents us with sugar of starch, not with 

 dextrine, it is evident that the globules of the pericarp must either con- 

 tain this sugar ready funned and prepared to be absorbed by the young 

 ovary, or that the globules are accompanied by a principle analogous 

 to diastase, which breaks them and converts their dextrine into sugar, 

 as in germination. 



After fecundation is effected the composition of the ears is greatly 

 altered. On the 15th of June the young grains of rye, taken from 

 the ears, contained grains of starch ready formed, which were visible 

 with the microscope. They burst under the influence of sulphuric 

 acid and disengaged a substance soluble in water and precipitable by 

 alcohol, which is ascertained to be dextrine by the great energy of 

 its rotatory power compared with its density. Sugar of starch ready 



