396 BOTANICAL GAZETTE [JUNE 
That cane sugar may find its way directly into the fruit would 
seem probable, moreover, since it is one of the most diffusible carbo- 
hydrates, and Brown and Morris’? believe it the primary carbohy- 
drate synthesized by the chloroplasts. Cane sugar, however, is not 
suited to nourish the protoplasm. If injected directly into the blood 
of animals, BERNARD'S has shown it to be eliminated unchanged by 
the kidneys, and to be inverted in the beet root before being used. 
Glucose appears in the beet root and can be traced up the stem, but 
Not so with cane sugar. Forbes’? finds the same true with canaigre, 
Rumex hymenosepalus. The small amount of cane sugar contained 
in the dormant root suddenly decreases when the root begins to send 
up a stalk. The much larger amount of starch is similarly affected. 
As is well known, the moving carbohydrate of the maple is nearly 
pure cane sugar. Plant leaves are also known to contain invertase in 
conjunction with cane sugar. Brown and Morris consider the entire 
amount of cane sugar to be hydrolyzed, first for the nutrition of the 
tissues, and then any excess to be resynthesized into starch for future 
use, the hydrolytic product of this starch being maltose. It appears 
thus that either cane sugar, invert sugar, or maltose has the oppor- 
tunity of leaving the leaf. SAPoSCHNIKOFF?° says the form in which 
the carbohydrate leaves the leaf is unknown, but is probably glucose. 
It has been established, on the other hand, that the existence of 
starch in the tuber of the potato,?* in maize,?? and in wheat?3 depends 
on the previous existence of cane sugar in the juice of these plants. 
Kerm,?4 in Hitcer’s laboratory, found cane sugar to accumulate in the 
leaves of the cherry and.starch in the fruit stems during the growing 
stage, both of which disappear at the period of maximum ripening, 
when a small amount of very transient cane sugar is found in the 
17 A contribution to the chemistry and physiology of foliage leaves. Jour. Lond. 
Chem, Soc. 63:604. 1893. 
78 GREEN, The soluble ferments rro. Cambridge 1899. 
19 Unpublished papers. 
20 Bildung und Wa a der Kohlenhydrate in der Laubblattern. Ber. 
Deutsch. Bot. Gesells. 8:233. 1890. 
2x GIRARD, Compt. yest 108:602. 1889. 
:22 ZEPLEY, Compt. Rend. 94:1033. 1882. 
23 BALLAND, Compt. Rend. 106:1610. 1888. 
24 Loc. cit. 
