THE CEREALIA. 25 



should continue to set more and more strongly towards 

 that quarter, so as to call for a proportionately in- 

 creased quantity of grain for the sustenance of the 

 settlers. 



Humboldt, in his account of New Spain, has given 

 a very interesting view of the agriculture of South 

 America, In the lower latitudes of the Mexican 

 republic, the cereal grains of Europe, comprehending 

 under this denomination wheat, barley, oats, and rye, 

 are never cultivated at a lower elevation than from 

 2500 to 3000 feet above the level of the sea. It is 

 well known that the habitation of plants is determined, 

 in a very decided manner, by the elevation of different 

 regions. On this subject De Candolle calculates, 

 that in France every five hundred and forty feet of 

 vertical elevation is equivalent to a receding of one 

 degree from the equator ; while Humboldt estimates 

 every rise of three hundred and ninety-six feet to be 

 equal to the same advance to the north, in tropical 

 countries. We know that the summits of the towering 

 Andes some of which are placed almost directly 

 under the equatorial line are yet covered with per- 

 petual snow ; and that in many mountainous countries 

 within the tropics, the seeds and fruits of temperate 

 regions are seen to flourish. 



On the declivity of the Cordilleras, between Vera 

 Cruz and Acapulco, wheat cultivation does not in 

 general commence at a lower level than 4000 feet. 

 Sometimes, as in the immediate vicinity of the city of 

 Xalapa, wheat is sown, not for the sake of the grain, 

 which indeed it there never produces, but because 

 the straw and succulent leaves furnish excellent fodder 

 for cattle. 



It does not appear, however, that the degree of 

 latitude and the amount of elevation are the only cir- 

 cumstances that determine the fructification of wheat, 

 since in Guatemala, which is nearer to the equator, 



VOL. xv. 3 



