INDIGO 235 



. ,iiirely superseded the use of woad, which for many centuries 

 liad served to dye the blue broad cloths and linens of the 

 iMiropean weavers. 



\^arious species of indigo plants or indigoferas. are found 

 flowing spontaneously in the warmer countries of both hemis- 

 ])licres, but the indigofera tinctorla is most generally cultivated, 

 from its yielding a greater quantity of pulp. The knotty 

 shrubby plant rises about two feet from the ground ; the leaves 

 aro winged like those of the acacia, smooth and soft to the 

 touch, furrowed above, and of a darker colour on the upper than 

 til (3 under side. The small reddish flowers which grow in ears 

 from the axillae of the leaves have no smell, and are succeeded 

 ])\ long crooked brown pods, which contain small yellow seeds. 

 T1k3 plant requires a smooth rich soil, well tilled, and neither 

 too dry nor too moist. A child of the sun, it cannot be 

 advantageously cultivated anywhere except within the tropics, 

 a higher mean temperature than 60° being absolutely necessary 

 for its vegetation. The seed is sown in little furrows about the 

 breadth of the hoe, and two or three inches in depth. These 

 furrows are made a foot apart from each other, and in as straight 

 a line as possible. Soon after sowing, continual attention is 

 , required to pluck the weeds, which would quickly choke up the 

 ' plant and impede its growth. Sufficient moisture causes it to 

 slioot above the surface in three or four days, and it is usually 

 fit for gathering at the end of two months. WTien it begins to 

 flower it is cut with a sickle a few inches above the roots, and 

 furnishes, after six or eight weeks, a second crop. In the 

 countries most favourable to its growth the planter is even 

 able to cut it four times in one year; but as the produce 

 1 diminishes fast after the second cutting, the seeds must annually 

 I be sown afresh. 



j The cultivation of indigo would thus seem to be extremely 

 I profitable, but the sun, which so rapidly improves and invigo- 

 rates the plant, calls forth at the same time a multitude of 

 insects and caterpillars, that prey upon the valuable leaves, and 

 ■ frequently disappoint the planter's expectations. 



The colouring matter of indigo is not ready-formed in the 



plant, but requires fermentation and contact with the oxygen of 



> the air to attain the deep cerulean tint which renders it so 



I valuable. The herb is first put into a vat or cistern called the 



