PART I. 
NATURAL ORDER. — EUPHORBIACEiE. 
1. American Sources oe Supply. 
Hevece Species , “ Para Caoutchouc.” 
Of all the various kinds of Caoutchouc, that of Para is the most 
highly esteemed, and consequently obtains the highest price. It is 
furnished by different species of the genus JSevea , AubL, or Siphonia , 
Rich. It, too, is one of the most important articles of export at 
Para, the duty on it being stated to form a third of the whole 
revenue. The travels of Messrs. Edwards,* * * § Bates,! and Wallace, J 
and Dr. Spruce, § have added materially to our knowledge of these 
trees and their produce. They are found abundantly in the 
provinces of - the Amazons and of Para, less common in Maianliam, 
and in large quantities in Ceara and Rio Grande du Nord ; 
frequenting the river banks and marshy places. To the accmacy, 
• industry, and perseverance of Dr. Richard Spruce, ^however, we are 
indebted for nearly the whole of our present information respecting 
the species yielding this important substance, and till his tune 
unknown. 
The Heveas are large trees, the trunks of which yield a very pure 
Caoutchouc, growing abundantly in the humid forests of tropical 
America, especially along the Amazon and its tributaries. . The 
wood is soft and soon decaying, partly owing to the “tapping 
operation to which they are subjected. The seeds are used for 
baiting fish, and also yield by expression an oil of a clear violet 
colour, not so siccative as that of linseed oil, but said to be of great 
use in the preparation of varnishes. 
* Edwards, “ A Voyage up the River Amazon,” New York, 1847. 
f Bates, “ Naturalist on the River Amazon,” 2 vols., London, 1863. 
j Wallace, “ Travels on the Amazon and Rio Negro,” London, 1853. 
§ Spruce in “ Hooker’s Journal of Botany,” 1854, et seg., and in Letters to Collins. 
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