Notwithstanding this seeming permanence of type, it is well known that of all physical conditions, color is the most liable to change in every organism. Many animals under domestication change their color entirely.[298] In our Southern States it was observed that house-slaves of the third generation presented quite a markedly different appearance from field slaves.[299] This was owing as much, no doubt, to different food and different habits of life as to protection from the sun, though many different races have quite the same color while their habits of life are as different as well could be imagined. Of this class, the Eskimo, Chinese, and Fuegeans are examples. However, the fact that color is variable even in a slight degree, indicates that considerable if not radical changes might be brought about during a great length of time. Mr. Darwin has furnished the most rational solution of the question, which he describes briefly as follows: “Various facts which I have elsewhere given, prove that the color of the skin and hair is sometimes correlated in a surprising manner with a complete immunity from the action of certain vegetable poisons and from the attack of parasites. Hence it occurred to me that negroes and other dark races might have acquired their dark tints by the darker individuals escaping during a long series of generations from the deadly influence of the miasmas of their native countries.”[300] This doctrine of the survival of only the fittest, while all the weaker and perhaps lighter complexioned individuals of a race gradually succumbed to the deadly influence of climate, no doubt will explain the origin of the dark races, known to enjoy a special immunity against yellow and other fevers.[301] At all events, the formation of the distinctive features of races requires a great lapse of time. The geologist asks for time in which to account for the formation of strata, and the intelligent world now grants it to him without limit, and just as reasonably may the ethnologist ask for time in which to account for the formation of racial types.[302] Nor need the most literal interpreter of Genesis object to this demand on the ground of any conflict with the letter even of the historic narrative of the Pentateuch. The accepted chronology, based on Archbishop Usher’s interpretation, is no part of the text of Genesis. It is purely the product of his inadvertence and the blindness of many others of his school of Biblical chronologists. It is evident that the rules of interpretation applied to the tenth chapter of Genesis, according to which the names of the descendants of Noah’s sons are taken to represent individuals only, cannot hold. The probabilities are that they represent considerable tribes or nations. This probability is an established fact in the sixteenth and subsequent verses. In the fifteenth verse we learn that Canaan, the grandson of Noah, “begat Sidon, his first-born, and Heth.” Here