62 
EXHAUSTION OF THE SOIL. 
remark, that a great deal of cacao of an inferior quality, 
such as that of Maranon, the Rio Negro, Honduras, and 
the island of St. Lucia, bears the name, in commerce, of 
Guayaquil cacao. The exportation from that port amounts 
only to sixty thousand fanegas; consequently it is two- 
thirds less than that of tho ports of the Capitauia-General 
of Caracas. 
Though the plantations of cacao have augmented in the 
provinces of Cumana, Barcelona, and Maracaybo, in pro- 
portion as they have diminished in the province of Caracas, 
it is still believed that, in general, this ancient branch of 
agricultural industry gradually declines. In many parts 
coffee and cotton-trees progressively take place of the cacao, 
of which the lingering harvests weary the patience of the 
cultivator. It is also asserted, that the new plantations of 
cacao are less productive than the old; the trees do not 
acquire the same vigour, and yield later and less abundant 
fruit. The soil is still said to be exhausted ; but probably 
it is rather the atmosphere that is changed by the progress 
of clearing and cultivation. The air that reposes on a virgin 
soil covered with forests is loaded with humidity and those 
gaseous mixtures that serve for the nutriment of plants, 
and arise from the decomposition of organic substances. 
"When a country has been long subjected to cultivation, it 
is not the proportions between the azote and oxygen that 
vary. The constituent bases of the atmosphere remain 
unaltered ; but it no longer contains, in a state of suspen- 
sion, those binary and ternary mixtures of carbon, hydrogen, 
and nitrogen, which a virgin soil exhales, and which are 
regarded as a source of fecundity. The air, purer and less 
charged with miasmata and heterogeneous emanations, be- 
comes at the same time drier. The elasticity of the vapours 
undergoes a sensible diminution. On land long cleared, 
and consequently little favourable to the cultivation of the 
cacao-tree (as, for instance, in the “West India Islands), the 
fruit is almost as small as that of the wild cacao-tree. It is 
on the banks of the Upper Orinoco, after having crossed the 
Llauos, that we find the true country of the cacao-tree, 
thick forests, in which, on a virgin soil, and surrounded by 
an atmosphere continually humid, the trees furnish, from 
