102 
1,600 feet, and in the island of Cuba, in 20° north latitude, 
at still lower altitudes. Nay, in the isle of France, in 20° 
south latitude, it grows close to the sea shore. Similar 
instances have been observed in the island of Luqon, but 
here the mean heat is very much lowered by the prevailing 
monsoons. Wheat is cultivated at a great elevation on some 
of the uninterrupted plains of the Himalaya mountains, but 
probably higher on the plateau of Tacora, in the district of 
Cabul. It is cultivated in all parts of Chili, where there is 
sufficient water, from the sea, to a height of 5,200 feet, and 
the Chilian wheat is of excellent quality. 
The extraordinary productiveness of wheat in some tro- 
pical countries has been stated by Humboldt. In Mexico 
he observed wheat plants with 40, 60, and even 70 stalks, 
the ears of which were almost equally well filled, and con- 
tained from 100 to 120 grains each. In the equatorial part 
of Mexico the produce is twenty-four-fold, and in plentiful 
years thirty-five-fold. Yet, in the tropical parts of America, 
the yield of maize is eight hundred fold where it thrives 
best, in a hot and damp climate; and one hundred-fold is 
looked upon as a poor crop of this grain in tropical countries. 
Yet in colder countries the yield is still smaller. In Cali- 
fornia it is seventy-fold. 
In Mexico, (in the subtropical zone of Meyen,) between 
the parallels of 20° and 40° north latitude, the culture of 
wheat first begins at the height of 2,500 or 3,000 feet. 
At Vera Cruz and Acapulco, according to Humboldt, fields 
of wheat are first met with at the height of 3,600 feet, and 
ascend above 9,000 feet. On the plateau of Southern Peru, 
wheat fields, of extraordinary productiveness, lie at the 
altitude of 8,000 feet (Meyen) ; and at Cangallo, at the 
foot of the volcano of Arequippa, (south latitude 16°,) wheat 
succeeds well, even as high as 10,000 feet. In the North 
of Mexico the produce is seventeen-fold ; in La Plata twelve- 
