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 infectorius, a small shrub about five 

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

 an insect, Cynips galla-tinctoria. The puncture is effected 



