Man may be assumed to be prehistoric wherever his chroniclings of himself are undesigned, and his history is wholly recoverable by induction. The term has, strictly speaking, no chronological significance; but, in its relative application, corresponds to other archæological, in contradistinction to geological, periods. There are modern as well as ancient prehistoric races; and both are available for solving the problem of man’s true natural condition. But also the relation of man to external nature as the occupant of specific geographical areas, and subject to certain influences of climate, food, material appliances and conditions of life, involves conclusions of growing importance, in view of many novel questions to which the enlarged inquiry as to his true place in nature has given rise. If races of men are indigenous to specific areas, and controlled by the same laws which seem to regulate the geographical distribution of the animal kingdom, the results of their infringement of such laws have been subjected to the most comprehensive tests since the discovery of America. The horse transported to the New World roams in magnificent herds over the boundless pampas; and the hog, restored to a state of nature, has exchanged the degradation of the stye for the fierce courage of the wild boar. There also the indigenous man of the prairie and the forest can still be seen unaffected by native or intruded civilisation; while the most civilised races of Europe have been brought into contact with the African savage; and both have been subjected to all the novel influences in which the western continent contrasts no less strikingly with the temperate than with the tropical regions of the eastern hemisphere. The resultant changes have been great, and the scale on which they have been wrought out is so ample as to stamp whatever conclusions can be legitimately deduced from them with the highest interest and value. The consequences following from changes of area and climate play a remarkable part in the history of man, and have no analogies in the migrations of the lower animals. The Frank, the Anglo-Saxon, and the Norman; the Hungarian, the Saracen, and the Turk: are all to a great extent products of the transplanting of seemingly indigenous races to more favouring localities; but the change to all of them was less than that to which the colonists of the New World have been subjected. There the old process was reversed; and the offspring of Europe’s highest civilisation, abruptly transferred to the virgin forest and steppes of the American wilderness, was left amid the widening inheritance of new clearings to develop whatever tendencies lay dormant in the artificial European man.