162 POPULAE GEOGRAPHY OP PLANTS. 



hundred million pounds' weight of cotton every year, one- 

 twentieth only of which is brought from India. 



The Indigo-plant, which is to provide the dye for the 

 Cotton, grows in the same neighbourhood, and has been 

 before described as a little herbaceous plant with a papilio- 

 naceous flower. The species chiefly cultivated is Indigofera 

 tinctoria. The whole of the plant is pervaded with the co- 

 louring matter, so that, in preparing the dye, the entire 

 plants which are mowed down when in flower are plunged 

 into vessels of water; when the water has extracted the 

 dye, it is poured into other vessels, in which the dye soon 

 separates from it, and is precipitated to the bottom. When 

 first extracted it is yellow, but it becomes blue by exposure 

 to the air. The water is got rid of by boiling the whole 

 together till the water all evaporates in steam; when the 

 dye is put into wooden moulds, from which it takes the 

 shape in which it appears as an article of commerce. The 

 number of pounds brought to England from her different 

 colonies yearly is six millions and a half; of which two 

 millions are used in England, and the rest exported to the 

 Continent. It was impossible to pass by two such impor- 

 tant plants as Cotton and Indigo without giving the above 

 interesting details, from Meyen. 



