142 PLANT ANATOMY. 
ingly soluble milk-sugar, which does not, however, require more 
than seven parts of water for solution at the ordinary tempera- 
ture, has as yet been found but once (1871) in the vegetable 
kingdom, in the fruit of the tropical Achras Sapota L. 
Grape-sugar (Dextrose),’ deviating to the right, is of most 
frequent occurrence in the vegetable kingdom; it occurs, for 
instance, in grapes, figs, pears, cherries, in liquorice-root and in 
tamarinds. 
Fruit-sugar (Mucilage-sugar, Levulose *), deviating to the | 
left, is contained in honey, and often mixed with grape-sugar. 
Cane-sugar (Beet-root sugar, Saccharose), deviating to the 
right, is contained in the sugar-cane, sorghum, the sugar-beets, 
in carrots, and in the sap of the sugar-maple. By inversion ° it 
passes into a mixture of one molecule of grape-sugar (dextrose) 
and one molecule of fruit-sugar (levulose), the so-called invert- 
sugar‘; the latter is found in fruits and in honey. 
Mycose® (Fungus-sugar) is found in fungi, for instance, in 
ergot. 
Melitose* is found in the Manna obtained from the leaves of 
species of Hucalyptus (Australian Manna). 
Grape sugar is detected in the cells micro-chemically by 
Trommer’s reaction.’ The sections are placed successively in a 
concentrated solution of sulphate of copper in water (they 
should be well washed, but not too long), and in dilute caustic 
potassa, and boiled in the latter, If sugar be present, there is 
formed in the cells a red, granular precipitate of cuprous oxide, 
Cu,O. (The execution of this reaction requires experience. ) 
As aresult of incisions, there are formed in the Manna-ash 
1 Dexter, right. 
2 Leevus, left. 
5 By boiling with dilute acids. 
* Invertere, to invert, for the reason that invert-sugar deviates to the 
left, that is, in an opposite direction to cane-sugar, 
5 Moxos fungus. 
6 MéAz honey. 
‘Sachs, “ Microchem, Reactionsmethoden.” Wiener Academie. 
Sitzungsberichte, 1859. : 
