So is it also with those divisions, peculiar to India, which are known to us by the Portuguese name of _caste_. The Indian name for caste is _varna_, or "colour," and physical differences between different castes were fairly obvious even before accurate averages were struck between many individual measurements. Caste has undoubtedly tended, and for similar reasons, to perpetuate such differences between classes of men as we readily recognise between different breeds of horses or cattle. The ages of men succeed one another more slowly than the generations of domestic animals, and segregation, in spite of caste rules, has probably at no time been so rigid as in the case of pure-bred animals. But there is a restriction in the matter of marriage which has been more or less efficacious, and especially so in the case of the higher castes, where the women are more carefully guarded, and pride of birth influences the future mothers of the race. In some rare instances, castes are still racial, preserved from immixture by much the same feeling which leads the white American to protect his race from a mingling of Negro or Red Indian blood. Other castes are still recognisably the result and record of such forbidden mixtures. Sometimes the resulting difference is so great as to be visible in actual measurements. Often the result is a mere peculiarity of aspect, such as enables an expert to identify a mongrel or a crossbreed among domesticated animals. In any case, once a caste is formed, it is fenced in by matrimonial rules, strict in proportion to the social status and consideration of the group. Not only, then, are the racial origins of modern India more various than those of Europe, but such varieties of colour, stature, and culture as exist tend to be perpetuated.