Since 1840, notwithstanding the frequent wars, Mexico, in favored localities, may have slightly increased in population; but this increase is more than balanced by the Indian wars of the northern departments, which have depopulated large tracts of country, sometimes extending across one tier of states even into the heart of Durango and Guanajuato; so that I hazard nothing in affirming that the population of the whole country must be less to-day than it was in 1794, notwithstanding that Humboldt sets down an estimate of 5,800,000 for the year 1803, and 6,500,000 for the year 1808. I might go farther, and affirm that the constant insecurity of life and property in all but the central parts of the republic is such as to keep down the natural increase of a population never prolific, being made up of a combination of uncongenial races--whites and Indians, whose intermixture leads to sterility. The census shows two fifths of the population to be pure Indians, mostly laborers: this class would have been the one most likely to have increased since the Revolution, had there remained the same amount of employment and wages as formerly. In consequence of the abolition of monopolies, the articles necessary for the comforts of life became much cheaper and more easy of attainment to the laboring classes, which would tend to increase the number of this class. These Indians, moreover, had remained to a great extent free from the deleterious intermixture of white blood. But the pure Indian, compared with the pure Caucasian, is a race, under the most favorable circumstances, of slow increase. The diseases hereditary among the Indians are aggravated by promiscuous marriages, so that in California the missionaries used to inquire diligently after a man's family connections, and compel a convert to marry into his own clan, or not marry at all. The Meztizos, or mixed races, constitute another two fifths of the population. This is a less vigorous race than the pure Indian. They are all the children of sin, mostly the offspring of illicit intercourse, and are for this cause a feebler race than the offspring of the same mixture where the man was only blessed with a single wife. As all marriage of whites with Indians in New Spain was unlawful, these Meztizos bore the same relation to the law in New Spain which the mulattoes do in our Southern States. RACES IN MEXICO.