433 



the missions of San Miguel de Davipe, San Car- 

 los and Mandavaca. No doubt can be ad- 

 mitted, that several nations of America, par- 

 ticularly the Mexicans, long before the conquest, 

 employed real indigo in their hieroglyphical 

 paintings; and that small cakes of this sub- 

 stance were sold at the great market of Tenoch- 

 titlan*. But a colouring matter, chemically 

 identical, may be extracted from plants belong- 

 ing to neighbouring genera ; and I should not at 

 present venture to affirm, that the native indi- 

 goferce of America do not furnish some generic 

 difference from the indigofera anil, and the 

 indigofera argentea, of the ancient continent. 

 In the coffee-trees of the two worlds this differ- 

 ence has been observed. 



Here, as at the Rio Negro, the humidity of 

 the air, and the abundance of insects, which is 

 it's natural consequence, are obstacles almost 

 invincible to new cultivation. We never found 

 the hygrometer of Deluc, even when the sky 

 was serene and blue, below52°*f'. Every where 

 you meet with those large ants, that march in 

 close bands, and direct their attacks so much 

 the more on cultivated plants, as these are her- 



ca) 9 It is called cumapana, and is eaten baked on the ashes. 

 It grows spontaneously on the banks of the Cassiquiare. 



* See my Polit. Essay, vol. ii, p. 447. 

 + Eighty-^even degrees. Sauss. 

 VOL. V. 2 F 



