ON THE JUICE OF THE SUGAR-CANE. 423 
The analyses of one of these canes exhibits the largest relative 
quantity of uncrystallizable sugar which I have noticed. 
Q ( Crystallizable 8'6 
fcugar | xjncrystaUizable 2-4 
Water, &c, &c M ... 940 
It is important to remark that these "foolish" canes grow rapidly 
in the midst of extensive plantations which overshadow them, and they 
generally have a tender and uncoloured bark, one of the circumstances 
most favourable to the predominance ol interverted sugar. When the 
canes, on the contrary, grow regularly and slowly in a field which 
receives the direct action of light, they hardly ever contain in their 
middle portion, even when the stems begin to lose their leaves, more 
than one-tenth of interverted sugar in the whole weight of saccharine 
matter contained in the juice. This proportion of levulose rapidly 
diminishes as the cane stem still more disengages itself, unless its growth 
suddenly assumes an abnormal activity. 
5. Having admitted the preexistence of uncrystallizable sugar in the 
cane, it becomes important to know the precise nature of this substance, 
and to determine if it proceeds or follows the formation of the crystal- 
lizable sugar which is equally found there ; or in other words, if, by a 
process of modification, it gives rise to the former, or if on the contrary, 
it is not itself a product of the transformation of cane sugar properly so 
called. The inadequacy of the chemical means at present at command to 
isolate in a prompt and complete manner these two kinds of sugar with 
out changing their original character, will not perhaps, until after a long 
interval, allow us to formulate the composition of the interverted sugar 
peculiar to the cane. My own optical experiments made for the pur- 
pose of appreciating the rotatory power of this substance, have, I am 
forced to confess, given me as yet but very uncertain results. It can 
however, be concluded from these experiments that the liquid sugar of 
the cane generally turns the plane of the polarising saccharometer to the 
left ; that even this peculiarity is modifiable, and that under certain cir- 
cumstances it has the property of partially turning to the right, and of 
not being interverted by the action of diffusive acids, as though it were 
then formed of a portion of the power of turning to the right, and a 
portion of the power of turning to the left, which is non-iutervertable. 
Such an interpretation must be admitted in order to explain the contra- 
dictory indications furnished by the optical examination of the juice 
obtained from canes containing a high proportion of liquid sugar. 
When after having directly examined this liquid, and inter- 
verted it, we again submit it to polarised light, it generally happens 
as I have said above that a deviation to the left indicates a smaller 
quantity of interverted sugar than what is furnished by the chemical 
analysis ; but it also happens that the quantity is equal or only a little 
VOL. VJ. Y Y 
