66 THE AMERICAN JOURNAL OF SOCIOLOGY
At the same time, one discovers the law of social frontiers. These frontiers are in correlation with the organic composition of the social group, and especially with the economic elements which enter into that combination ; such is the general condition of the limitation of the group internally, besides the constant, necessary equilibrium with the external forces, sometimes social, some- times purely physical, as is shown by the following example: "Among the Andamenes," according to the same sociologist, " hemmed in between a straight line of seacoast, and impenetrable forests, forty is the number of individuals who can secure for themselves a living without going too far from home." This is done by a population almost all hunters.
Among the Bushmen, wandering over arid regions, only small hordes can exist, and the families are sometimes forced to separate because the same place does not give subsistence to all.
Let us now take peoples equally primitive, but living in more favorable places. According to Wallace, 1 the rhizomes of the Colocaria esculenta can support fifty-eight persons per hectara (requiring the work of only three persons). According to Humboldt, the product of the banana tree is to that of wheat as 133:1, and to that of potatoes as 44:1. The colocaria and the banana tree permit then, all other conditions being equal, the formation of a very dense population, whence result some internal molecular movements, more numerous and more active, and, at the same time, more energetic and more extended molar action and reactions, reacting to exterior social or sometimes purely physical forces. Wallace indicates further 2 that the facula- bearing stepe of the sago tree, which is sometimes twenty feet long and four or five feet in circumference, can be converted into nourishment by five days' work of two men and two women and which furnishes enough food for one man during a year, or for the four workers at least three months. If certain populations under these favorable conditions do not become more dense it is because of the intervention of other factors, either social or physical; for example, the tendency to idleness or their geo- graphical isolation. In general, the inferior social groups
1 Malay Archipelago, Vol. I, p. 303. 'Ibid., Vol. II, p. 68.
