Can we then consider this result as a sign of the ascendancy of the white race? I do not think so. I rather consider it as the consequence of the general tendency pointed out above. In the countries which we are discussing, the Negress or Indian woman readily crosses with the White. The female issue of these unions, proud of the blood of her father, would consider herself degraded if wedded to an individual of coloured race, and reserves all her favours for those to whom she approximates by reason of the crossing. The Quadroon reasons and acts in the same manner. In these regions, where colour decides caste, it is always men of whiter race, and especially the pure white, that the women prefer to marry. The consequence of this is, that the crossing, although apparently left to chance, is in reality _unilateral_, and always directed towards the superior race. It is accomplished under the influence of a real _unconscious selection_, and the predominance of the white blood is the result of this selection. Sooner or later it will also result in the fulfilment of the prediction of Martin de Moussy. The mixed races will in a great measure return to the superior race. But, when brought back to the white type by this circuitous path, and through all these degrees of crossing, they will possess one very great advantage over their European counterpart: they will be acclimatised. The reverse phenomena appear, according to Squiers, to be taking place in Peru. Here the mixed population tends to return to the indigenous type. The fact is explained, at least in part, by the relations which, since the commencement of the conquest, were established between the conquerors and the conquered race. The former could not affect unlimited contempt for a conquered race who were as civilised as themselves. Their leaders made alliances at an early period with the families of the Incas, and this example was followed. Consequently colour cannot exercise the same influence in Peru as in Brazil or at Buenos Ayres. The numerical predominance of the local race and the conditions of life had then a free field, and their double influence is shown in the result pointed out by Squiers. IX. Can human crossing, so general in our days, be a new phenomenon in the history of mankind? Evidently not. In the past as in the present, every contact between two races of any continuance, every immigration, and every conquest has led to the formation of a mixed race. It is one of the inevitable consequences of human instincts and of physiological laws.