What the Melting Pot actually does in practice can be seen in Mexico, where the absorption of the blood of the original Spanish conquerors by the native Indian population has produced the racial mixture which we call Mexican and which is now engaged in demonstrating its incapacity for self-government. The world has seen many such mixtures and the character of a mongrel race is only just beginning to be understood at its true value. It must be borne in mind that the specializations which characterize the higher races are of relatively recent development, are highly unstable and when mixed with generalized or primitive characters tend to disappear. Whether we like to admit it or not, the result of the mixture of two races, in the long run, gives us a race reverting to the more ancient, generalized and lower type. The cross between a white man and an Indian is an Indian; the cross between a white man and a Negro is a Negro; the cross between a white man and a Hindu is a Hindu; and the cross between any of the three European races and a Jew is a Jew. In the crossing of the blond and brunet elements of a population, the more deeply rooted and ancient dark traits are prepotent or dominant. This is matter of everyday observation and the working of this law of nature is not influenced or affected by democratic institutions or by religious beliefs. Nature cares not for the individual nor how he may be modified by environment. She is concerned only with the perpetuation of the species or type and heredity alone is the medium through which she acts. As measured in terms of centuries these characters are fixed and rigid and the only benefit to be derived from a changed environment and better food conditions is the opportunity afforded a race which has lived under adverse conditions to achieve its maximum development but the limits of that development are fixed for it by heredity and not by environment. In dealing with European populations the best method of determining race has been found to lie in a comparison of proportions of the skull, the so-called cephalic index. This is the ratio of maximum _width_, taken at the widest part of the skull above the ears, to maximum _length_. Skulls with an index of 75 or less, that is, those with a width that is three-fourths of the length or less, are considered dolichocephalic or long skulls. Skulls of an index of 80 or over are round or brachycephalic skulls. Intermediate indices, between 75 and 80, are considered mesaticephalic. These are cranial indices. To allow for the flesh on living specimens about two per cent is to be added to this index and the result is the cephalic index. In the following pages only long and round skulls are considered and the intermediate forms are assigned to the dolichocephalic group.