dient for tabulating their resemblances as that of arranging them in four intersecting sets of concentric circles.
One type, the latest arrival, would be represented by a series of larger and larger circles around a center—the center standing for the few individuals of pure blood; the next ring, overlapping the other sets a little, would represent those persons, more numerous than the pure specimens, in whom the characteristics of the race are slightly obscured by characteristics of the other types. The next still larger ring, intersecting still more rings in the other sets, represents the still greater number of individuals of less pure descent, and so on; each larger circle, intersecting the other sets at more points, will represent the manner in which the number of individuals increases as the purity of the type disappears.
The race which has been a little longer in the country will, if it has been equally prolific, and equally inclined to mix with the others, be represented by a system with no center, but with a few very small rings so near the center that they have few points of intersection with the other sets—that is, there will be a few persons with nearly pure blood, but none of perfect purity. The two older races will be represented by systems which are made up entirely of large intersecting circles. After his studies have earned him thus far, we may suppose the anthropologist to speculate how or why it is that the complicated resemblances of this mixed people should follow a system which admits of such a peculiar system of tabulation. He might perhaps invent an hypothesis to explain it—the hypothesis of immigration. As this hypothesis would account for all his facts, there would be a probability in its favor sufficient to justify him in following it out as far as possible, to see what it would lead to, and we may suppose him to continue his studies historically. He would now find that the number of pure specimens of the race which entered the country last was greater a few generations back than at present, while the number of persons who exhibit only slight traces of the characteristics of this race become less numerous as he traces the history backward. Going still further back he would find that the pure-blooded specimens of this race not only become more numerous in proportion to those of mixed blood, but also more restricted in their distribution over the country.
Still farther back he would find records of the entrance of a few perfectly pure representatives of this race into the country, and, continuing his studies, he would meet with no evidence of the presence of any of them before this date.
Continuing his studies he would find that the second race gradually became more pure and more restricted, and, although he might not meet with any record of their first appearance except vague and contradictory traditions, he would find that there was no mention of them in any of the records before a certain date. The older monu-
