226 



POPULAR ECONOMIC BOTANY. 



colour and hard glossy exterior ; the pericarp is rather soft^ 

 but the interior albumen is very hard^ and contains a large 

 quantity of tannin ; hence it is useful to the tanner as well 

 as the dyer^ both of whom use large quantities of this 

 product. The surface of the fruit has slight longitudinal 

 depressions^ which do not appear on the larger myrobalans. 

 The smaller ones^ besides this characteristic^ are pointed at 

 each extremity, which makes it probable that more than one 

 species is imported in the same lot. 



With alum this dye yields a good durable yellow, and 

 with salts of iron a black colour little inferior to that pro- 

 duced by oak-galls. The myrobalan has not been intro- 

 duced more than ten or eleven years, but so useful has 

 it been found, that it has become a very important article 

 in our produce markets, and its consumption is now fully 

 2000 tons per annum. 



Galls, Gall-Nuts, Oak-Galls, and Nut-Galls, are 

 excrescences formed upon the young twigs of the various 

 species of oak. Galls are also produced upon other plants, 

 but the nut-galls of commerce are produced on the species 

 of oak called Quercus infectoriiis, a small shrub about five 

 or six feet in height. They originate in the puncture of 

 an insect, Cpiijos gallce-tinctoria. The puncture is effected 



