206 A TEXT-BOOK OF BOTANY. 



tannin; the bark of several species of Pinus (Fam. Pinacese) 

 growing in southern Europe yields 7 to 10 per cent, of tannin; 

 the barks of the white spruce (Picea canadensis) of Canada, of 

 the larch (Larix laricina) of northern and northwestern part of 

 United States and Canada, and of the fir (Abies balsamea) yield 

 similar amounts of tannin as the barks of hemlock and pine. The 

 wood of chestnut (Castanea dentata, Fam. Fagaceae) yields 8' to 

 10 per cent, of tannin ; the bark of several species of Salix (Fam. 

 Salicacese) growing in northern Europe yields 3 to 12 per cent, 

 of tannin ; the bark of chestnut oak, white oak, red oak, etc. 

 (Fagacese), yields 12 to 15 per cent, of tannin; the scaly in- 

 volucres or acorn-cups (under the name of " Valonia ") of 

 several species of Quercus growing in southern Europe and 

 Levant yield 25 to 35 per cent, of tannin ; the fruit of Terminalia 

 Chebula (under the name of " Myrobalans ") yields 35 to 40 

 per cent, of tannin ; the stems and leaves of several species of Rhus 

 (Anacardiacese) yield 16 to 24 per cent, of tannin; the fruit of 

 Ccesalpinia coriaria (Fam. Leguminosse) (under the name of 

 "divi-divi") yields 30 to 50 per cent, of tannin; the wood and 

 the bark of several species of Schinopsis (Fam. Apocynaceae) 

 growing in South America yield from 15 to 23 per cent, of tannin, 

 which is usually found in commerce in the form of an extract 

 known as " Quebracho Extract " ; the bark of the common horse- 

 chestnut (Aisculus Hippocastanum, Fam. Sapindaceae) yields 

 considerable tannin, and is employed in Italy ; the bark of Myrica 

 Nagi (Fam. Myricaceae) contains n to 14 per cent, of tannin; 

 the bark of Malpighia glabra (Malpighiaceae) (under the name 

 of "Nance bark") is used in Mexico and yields about 26 per 

 cent, of tannin; the bark of Stryphnodendron polyphyllum (Fam. 

 Leguminosae) yields about 30 per cent, tannin. The tannin of a 

 number of other plants has been investigated, some of these being 

 used in medicine, as granatum, catechu, kino, krameria, tor- 

 mentilla, gambir, etc. (see Vol. II). 



GALLS. There are a number of excrescences, found upon the 

 leaves and twigs of a number of plants, termed galls. These result 

 from injuries caused chiefly by insects, and are therefore in the 

 nature of pathological products. Galls which are formed on 

 trees which in themselves contain considerable tannin usually 



