62 EXHAUSTION OF TITE SOIL. 



remark, that a groat deal of cacao of an inferior quality, 

 such as that of Muranon, the liio 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 the ports of the Capitania- 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 

 Llanos, 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 tree? furnish, from 



