522 



SACCHARINE SUBSTANCES 



Constituents. Manna consists principally of mannite (mannitol), 

 C 6 H 8 (OH) 6 , of which it may contain from 40 to 60 per cent. Mannite 

 is I. a well-defined, crystalline substance belonging to the class of 

 alcohols (a hexahydric alcohol), and is widely diffused throughout 

 the vegetable kingdom. It is associated in manna with two sugars, 

 viz. manninotriose (6 to 16~>per cent.) and manneotetrose (12 to 16 

 per cent.). Each molecule of manninotriose 

 yields by hydrolysis two molecules of galac- 

 tose and one of dextrose ; each molecule of 

 manneotetrose yields two of galactose and 

 one each of dextrose and levulose. Dextrose, 

 mucilage, inorganic substances, a minute 

 quantity of a fluorescent substance, fraxin, 

 and about 10 per cent, of moisture also occur 

 in manna. 



Uses. Manna is used medicinally as a gentle 

 laxative. 



Allied Drugs. Australian manna obtained from 

 Myoporum platycarpum, Robert Brown (N.O. Poly- 

 galece), in brownish masses containing about 89 per 

 cent, of mannite. 



Alhagi manna from Alhagi Maurorum, Tournefort 

 (N.O. LeguminoscK), Persia, in brownish, brittle, crys- 

 talline or amorphous masses; consists chiefly of sucrose; 

 contains no mannite. 



Tabashir or Bamboo manna secreted in the surface 

 of the stem of Bambusa stricta, Roxburgh (N.O. 

 Graminece), almost entirely sucrose (not to be con- 

 founded with the tabashir which occurs in the interior 

 of the stem and is mainly silica). 



Oak manna, secreted in the leaves and acorn cups 

 of Quercus Vallonea, Klotschy (N.O. Cupuliferce), con- 

 sists of sucrose and dextrose ; contains no mannite. 



Tamarisk manna, from Tamarix gallica, var. 

 mannifera, Ehrenberg (N.O. Tamariscinece), contains 

 sucrose, 55 per cent. ; levulose, 25 per cent. ; no 

 mannite. 



Brianqon manna secreted by the leaves'of Larix europoea, de Candolle (N.O. 

 Coni/erce) contains the sugar melezitose. 



FIG. 244. Portion of 

 the stem of a Manna 

 tree, showing the 

 incisions and ad- 

 hering manna. Re- 

 duced. (Vogl.) 



HONEY 



(Mel) 



Source, &c. Honey is a saccharine substance deposited by the hive 

 bee, Apis mellifica, Linne (Phylum Arthropoda, Class Insecta, Order 

 Hymenoptem), and other species of Apis in the cells of the honeycomb. 



