BOTANY. 211 



plant. The produce of the cotton-tree (the bombax) 

 is not used in any fabric. The cotton-plant of the 

 United States is an annual, but in Columbia it is a 

 perennial, and will continue productive, bearing for 

 five or six years. 



Odours. 



The particular odours of plants seem in all cases 

 to depend upon the peculiar volatile oils they con- 

 tain. By collecting the aromatic oils, the fragrance 

 of the flower, so fugitive in the common course of 

 nature, is preserved, and as it were embodied and 

 made permanent. 



Aromatic Oils. 



Volatile or odorous substances seem particularly 

 destructive to the minute insects and animalcules, 

 that feed on the substance of the vegetables. 



Thousands of aphides may usually be seen in the 

 stalk leaves of the rose, but none are ever observed 

 in the flower. The woods that contain aromatic oils 

 are remarkable for their indestructibility, and for 

 their exemption from the attacks of insects, which is 

 particularly the case with the cedar, rose-wood, and 

 cypress. 



Rouge. 



The yellow colouring matter of flowers is the 

 most permanent. The carthamus contains a red and 

 yellow colouring matter; the latter is easily dissolved 

 by water, and from the red, rouge is prepared by a 

 process which is kept secret. 



Gum. 



The characteristic properties of gum are its easy 

 solubility in water, and its insolubility in alcohol. 



