Secondly, we have the important fact, which Mr. Lang has duly noted, though he does not apparently see its significance in the argument as to origins, that the class system "arose in a given centre and was propagated by emigrants and was borrowed by distant tribes."[385] Messrs. Spencer and Gillen distinctly affirm that the "division into eight has been adopted (or rather the names for the four new divisions have been) in recent times by the Arunta tribe from the Ilpirra tribe which adjoins the former on the north, and the use of them is at the present time spreading southwards."[386] This view is supported by the widespread organisation of eaglehawk and crow, and by the general homogeneity of Australian social forms. It is clear, therefore, that room is made for the external organisation of the class system and the consequent production of the dual characteristics of the Arunta--the joint product of the fossilisation of mother-right society at the end of the migration movement, and the superimposing upon this fossilisation, with its tendency towards the class system, of the fully organised class system. The two systems are not now fully welded in the Arunta group. Whatever view is taken of these, whether they be considered advanced or primal, the undoubted dualism has to be accounted for, and the best way of accounting for this dualism is, I submit, that of differential evolution. Further study of Messrs. Spencer and Gillen's work, together with the criticisms of various scholars, Mr. Lang, Mr. Hartland, Mr. Frazer, Mr. Thomas, and others, convinces me that the extreme artificiality of the class system is due partly to a want of understanding of the entire facts, and partly to the _ad hoc_ adoption by the natives themselves of new plans to meet difficulties which must arise out of a too close adhesion to their rules. Mr. Lang has allowed me to see a manuscript note of his, in which he points out that the inevitable result of the one totem to the one totem rule of marital relationship,--that is, totem A always intermarrying with totem B, males and females from both totems, and with no others,--is the consanguineous relationship of all the members of the two totems. The rule for non-consanguineous marriage has therefore broken down, and when it breaks down the Australian introduces a new rule which satisfies immediate necessities. When this in turn breaks down a further new rule is made, and this is the way I think the differing rules resulted. They represent, therefore, not varying degrees of culture progress, but only varying degrees of artificial social changes, and they spring from the oldest conditions of all where there is no class system at all.[387] Arunta society is not a "sport" under this view, but a product--a product to be accounted for and explained by anthropological rules, derived not only from Australian society but from the general facts of human society which have remained for observation by the science of to-day. The