22 
PLANT MORPHOLOGY. 
cus muscarius — the latter containing as much as 10 
per cent, in the dried plant. 
Mannit occurs as needles or prisms and is found in 
the manna of Fraxinus ornus to the extent of 90 
per cent. It is also found in some of the Umbelliferae, 
as Apiurn graveolens, and in some of the fungi and sea- 
weeds. 
Dulcit, which is closely related to mannit, is found in 
Euonymus Europeus and in most of the genera of the 
Scrophulariaceae. 
Melizitose is closely related to saccharose, and is 
found in the manna of Pinus larix and in the 
“ Manna of India,” the product of Alhagi maurorum. 
Melitose is found in the manna from Eucalyptus 
viminalis, of Australia. 
Gentianose occurs in the root of Gentiana lutea. 
2. TANNIN AND TANNOIDS. 
Tannins are asiiingent principles which produce 
blue or green precipitates with iron salts. The tan- 
noids, in addition, precipitate albuminous compounds, 
and when applied to animal hides convert them into 
leather. These principles are widely distributed, occur- 
ring dissolved in the cell sap, in parenchyma c*lls or 
in distinct reservoirs or vessels, and vary in amount 
from 1 per cent, or less to as high as 70 per cent, 
in Chinese galls. Tannin occurs in relatively large 
amount in the following families : Anacardiaceae, 
Cornaceae, Cupuliferse, Ericaceae, Geraniaceae, Hama- 
melidaceae, Lythariaceae, Leguminoseae, Labiatae, 
Plumbaginaceae, Pol) golaceae, Polygonaceae, Ranuncu- 
laceae, Rosaceae, Rubiaceae, Salicaceae, Saxifragaceae. It 
not only occurs in the normal cells of plants but also in 
the excrescences known as galls, which are produced by 
the sting of various species of Cynips and Aphis. 
