198 THE POPULAR SCIENCE MONTHLY. 



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 Lfctle 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 repre- 

 sented 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, con- 

 tinuing 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 gradu- 

 ally 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- 



