But there is in this no occasion to deduce a conclusion of fatalism. These limitations have been operative in great measure because they have been unrecognised, and no effort has been made to escape them. Though they may not be remedied, their evil effects may be avoided by enlightened prevision. They act like other natural laws, and all such laws can be turned to man’s advantage, if he sets about it wisely. MODES AND RATES OF ETHNIC VARIATION.—Both progressive and regressive mental variations are formed of constructive, synthetic evolution; both are necessary to general advancement; both have their place in the scheme of national health and growth. They belong among what the physiologist calls “anabolic” processes—those whose tendency is to preserve and develop the species. There has, however, been frequent misunderstanding of the modes of action of these processes and the rate of their movement. This misconception exists widely to-day. Many writers have mistaken actual advance for degeneration, or claimed that some nation or stage of culture was superior to another from some single real or imagined feature. Thus Rousseau and his school, enamoured of the supposed personal freedom of the savage, lauded the existence of man “in a state of nature”; and their followers still assail modern civilisation as a failure. It becomes important, therefore, to examine the modes of healthy progress so that we may understand its sometimes strange aspects. These modes are three in number: 1. In lines, either parallel (homoplastic) or divergent (heteroplastic). 2. In circles, or curved forms (spirals). 3. In waves, rhythmic undulatory forms. 1. _Parallel and Divergent Variation._—Evolutionists are familiar with these two forms of progressive variation in the organic world. They are equally evident in human progress. No fact in ethnology is more striking than the parallelisms of primitive culture. Go where we will among the savage tribes of the globe, we find them developing the same arts along the same lines, framing their tribal organisations on the same models, calling in similar words on the same gods. Not only in this but in what seem matters of caprice, fancy, and local colour, the same similarity, almost identity, prevails. They tell stories of like plots, decorate their weapons in like patterns, dance and sing in like forms. Yet, though so much alike, so “tarred with the same stick,” each tribe and group is different. Each has its own imprint and character. Each has its points of individuality. This is “divergent” variation, just as universal, just as inevitable as the parallelism we have been considering. This extends into minute and seemingly unimportant details. We may, for example, compare the stone axes of neighbouring American tribes. In a casual survey, they look alike; a close inspection reveals slight but constant differences. The trained eye can distinguish their place of origin without difficulty.