Page:Vol 3 History of Mexico by H H Bancroft.djvu/777

Rh was introduced in 1520 by one of Narvaez' vessels, and committed such havoc that many districts became almost depopulated. Its recurrence may be placed at about every eighteenth year; and although later attacks did not equal the first, yet they committed great havoc. Inoculation was introduced during the latter half of the eighteenth century, but not properly made known, nor much appreciated; vaccination on the other hand received immediate acceptance. Viceroy Iturrigaray brought it with him in 1803, as we have seen, and in the following year the special commission from Spain secured its general application.

Vómito prieto, the name in New Spain for yellow-fever, had at least this difference from the matlazahuatl, that it was confined to the low-lying coast, and seldom attacked those born in such regions; it gathered victims chiefly among visitors from cooler climates, sometimes every year during the hot term, sometimes with an intermission of several years, yet ever infusing terror among the fleets, so that both vessels and caravans sought to avoid its dreaded hot-bed, the region of Vera Cruz, the west coast so far being free from it. Arguments have been adduced to show that it was not known till the beginning: of the eighteenth century, but the records are probably at fault. Its development depending on certain condition, as shown sufficiently in the preceding brief remarks, the growth from an ever present germ was gradual, the full effect appearing only in later times. Who can gainsay that the sudden and extensive mortality recorded among arrivals at Vera Cruz even during the sixteenth century was not due to a form of this disease? Famine cannot be classed as less destructive than