territorial in its nature; membership of it does not depend among the Australians on any supposed descent from a common ancestor; and though residence plus possession of a common speech is mentioned by Howitt as the test of tribe, it is possible in Australia, under certain conditions1, to pass from one tribe to another in such a way that we seem reduced to residence as the test of membership. This change of tribe takes place almost exclusively where tribes are friendly, so far as is known; and we may doubt whether it would be possible for a stranger to settle, without any rite of adoption, in the midst of a hostile or even of an unknown tribe; but this is clearly a matter of minor importance, if adoption is not, as in North America, an invariable element of the change of tribe. Although membership of a tribe is thus loosely determined, tribesmen feel themselves bound by ties of some kind to their fellow-tribesmen, as we shall see below, but in this they do not differ from the members of any modern state.

But in Australia the importance of the tribe, save from an economic point of view, as joint owner of the tribal land, is small compared with the part played in the lives of its members by the intratribal associations, whose influence is recognised without, as within the tribe. These associations are of two kinds in the lowest strata of human society; in each case membership is determined by birth and they may therefore be distinguished as natal associations. In the one case, the kinship groups such as totem kins, phratries, etc., an individual remains permanently in the association into which he is born, special cases apart, in which by adoption he passes out of it and joins another by means of a legal fiction2. The other kind of association, to which the name age-grades is applied, is composed of a series of grades, through which, concomitantly with the performance of the rites of initiation obligatory on every male member of the community, each man passes in succession, until he attains the highest. In the rare cases where an individual fails to qualify for the grade into which his coevals pass, and remains in the grade of "youth" or even lower grades, he is by birth a member of one class and does not remain outside the age-grades altogether.

In the element of voluntary action lies the distinction between age-grades and secret societies, which are organised on identical or similar lines but depend for membership on ceremonies of initiation, alike in the lowest as in the highest grade. Such societies may be termed voluntary. The differentia between the natal and the voluntary association lies in the fact that in the former all are members of one or other grade, in the latter only such as have taken steps to gain admission, all others being simply non-members.

Although primâ facie all these forms of association are equally entitled to be classed as social organisations, the use of this term is limited in practice, at any rate as regards Australia, and is the accepted designation of the kinship form of natal associations only; for this limitation there is so far justification, that though they perhaps play a smaller part in the daily life of the people than the secret societies of some areas, with their club-houses and other features which determine the whole form of life, the kinship associations are normally regulative of marriage and thus exercise an influence in a field of their own.

Marriage prohibitions in the various races of mankind show an almost endless diversity of form; but all are based on considerations either of consanguinity or kinship or on a combination of the two. The distinction between consanguinity and kinship first demands attention; the former depends on birth, the latter on the law or custom of the community, and this distinction is all-important, especially in dealing with primitive peoples. With ourselves the two usually coincide, though even in civilised communities there are variations in this respect. Thus, according to the law of England, the father of an illegitimate child is not akin to it, though ex hypothesi there is a tie of blood between them. In England nothing short of an Act of Parliament can make them akin; but in Scotland the subsequent marriage of the father with the mother of the child changes the legal status of the latter and makes it of kin with its father. These two examples make it abundantly evident that kinship is with us a matter of law.

Among primitive peoples kinship occupies a similar position but with important differences. As with us, it is a sociological fact; custom, which has among them far more power than law among us, determines whether a man is of kin to his mother and her relatives alone, or to his father and father's relatives, or whether both sets of relatives are alike of kin to him. In the latter case, where parental kinship prevails, the limits of the kin are often determined by the facts of consanguinity. In the two former cases, where kinship is reckoned through males alone or through females alone, consanguinity has little or nothing to do with kinship, as will be shown more in detail below.

Kinship is sociological, consanguinity physiological; in thus stating the case we are concerned only with broad principles. In practice the idea of consanguinity is modified in two ways and a sociological element is introduced, which has gone far to obscure the difference between these two systems of laying the foundations of human society. In the first place, custom determines the limits within which consanguinity is supposed to exist; or, in other words, at what point the descendants of a given ancestor cease to be blood relations. In the second place erroneous physiological ideas modify the ideas held as to actually existing consanguine relations, as we conceive them. The latter peculiarity does not affect the enquiry to any extent; it merely limits the sphere within which consanguinity plays a part, side by side with kinship, in moulding social institutions. If an Australian tribe, for example, distinguishes the actual mother of a child from the other women who go by the same kinship name, they may or may not develop on parallel lines their ideas as to the relation of the child and his real father. Some relation will almost certainly be found to exist between them; but it by no means follows that it arises from any idea of consanguinity. In other communities potestas and not consanguinity is held to determine the relations of the husband of a woman to her offspring; and it is a matter for careful enquiry how far the same holds good in Australia, where the fact of fatherhood is in some cases asserted to be unrecognised by the natives. In speaking of consanguinity therefore, it must be made quite clear whether consanguinity according to native ideas or according to our own ideas is meant.

The customary limitations and extensions of consanguinity, on the other hand, cause more inconvenience. They are of course sometimes combined with the other kind, which we may term quasi-physiological, but with this combination we need not deal, as we are concerned to analyse only on broad lines the nature of these elements. Just as, with us, kinship and consanguinity largely coincide, so with primitive peoples are the kinship organisations immense, if one-sided, extensions of blood relationship, at all events in theory. In many parts of the world a totem kin traces its descent to a single male or female