Our collection of material for an argument will be complete when I have added that the trees most prolific of artificial fruit die the earliest, and suffer most from running sores; that the vines cultivated artificially to produce the choicest wines suffer most from the mildew, and the potatoes of the most artificial varieties are the ones that have suffered most from the rot. When the cholera first visited Mexico, its passage through the country was like the ravages of the Angel of Death among the Meztizos and the fragments of decaying races. And this progress toward depopulation can not be stayed by the infusion of a vigorous stock. The law of sexuality in plants leads to the intermarriage of the vigorous with the decaying and the intermixture of blossoms; nor can human plants long vegetate together without intermarriages, which ingraft the vigorous constitutions with the virus of the old and decaying. PROSPECTS OF MEXICO. If, then, I have correctly enunciated the law of migration of men, animals, and plants, and if the law of intermixture of distinct races, or distinct species of the race, has been truly stated, the important argument to be drawn from it, which interests all Americans inquiring into the future of Mexico, is, that the present incongruous fragments of population which the internal disorders of Spain have set loose in Mexico can never be transformed into a homogeneous nationality, nor can sufficiently permanent elements of strength be found in this political chaos to constitute a permanent government. The degraded condition to which labor is reduced forbids the idea of an immigration of foreign laborers, while the miserable scale of wages--a quarter of a dollar a day upon the estates, payable out of the plantation store, or three shillings in the towns--holds out no inducement for poor men of a healthy race to abandon their own country and migrate to Mexico in sufficient numbers to form a substratum of society which ultimately might rise into a nationality.