A certain number of tribes spread northwards, following the reindeer and other animal species which they had been accustomed to regard as necessary to their existence; they emigrated in latitude. Others from the same motive emigrated in altitude, accompanying the chamois and bouquetin into the mountain chains, which had been liberated by the melting of glaciers. Others, again, remained stationary. The two first groups were free for a much longer time from the influence of ethnical mixture. The tribes composing the third soon found themselves in the presence of brachycephalic and dolichocephalic immigrants of the polished stone period, and were easily subjugated and absorbed by them. XI. On their arrival in Europe, the men of the polished stone period did not meet only with those races which we have been discussing. They came in contact with all the quaternary races. This is proved by many of the facts already mentioned; and is proved merely by the magnificent collection of skulls and skeletons collected by M. de Baye from the sepulchral grottoes of the Marne. With the exception of the Canstadt type, all those which we have just described seem to have met together in this remarkable locality. Even that of La Truchère is represented by a head almost as strongly characterised as that of the Seille. The foundation of this neolithic population still belonged, however, to a newly arrived type. It is scarcely necessary to add that, whether old or recent, all these races have intermingled, and that the crossing is betrayed sometimes by the fusion, and sometimes by the juxtaposition, of characteristics. Either by infiltration or conquest, new races mingled with the preceding, before even the arrival of the Aryans. The latter spread to the western extremities of the continent, leaving extensive regions on the north and the south, where their predecessors continued to exist. Then followed historic invasions. It is from the mixture of all these elements brought together by war, and fused by the experiences of peace, that our European societies have been formed. XII. Man has been the sole essential agent in the formation of fresh ethnical groupings. From the earliest times of the polished stone period, land and climate have remained unaltered in our western world. European man has then been at liberty to obey the laws of his evolution, to found, modify, or destroy his associations and his societies, to traverse the ages of bronze and iron as well as historic times, without having to battle with those invincible forces, which perhaps arrested the development of the hunters of Cro-Magnon.