Among the aborigines of America, North and South, actual wife-purchase, both by service and by property rendered, is exceedingly common; though in some tribes, as in other parts of the world, the transaction takes the form of a simple exchange of gifts or of a bestowal of presents upon the bride's parents. The price is usually paid in horses, but many other forms of property are employed. Among the Kwakiutl, says Boaz, marriage "must be considered a purchase, which is conducted on the same principles as the purchase of a copper. But the object bought is not only the woman, but also the right of membership in her clan for the future children of the couple." For "many privileges of the clan descend only through marriage upon the son-in-law of the possessor, who, however, does not use them himself, but acquires them for the use of his successor. These privileges are, of course, not given as a present to the son-in-law, but he becomes entitled to them by paying a certain amount of property for his wife. The wife is given to him as a first instalment of the return payment. The crest of the clan, its privileges, and a considerable amount of other property besides, are given later on, when the couple have children, and the rate of interest is the higher the greater the number of children. For one child 200 per cent. of interest is paid; for two or more children 300 per cent. After this payment the marriage is annulled, because the wife's father has redeemed his daughter. If she continues to stay with her husband, she does so of her own free will.... In order to avoid this state of affairs, the husband often makes a new payment to his father-in-law" so that he "may have a claim to his wife."[598] [598] BOAZ, "Kwakiutl Indians," _Rep. Smith. Inst._, 1895, _Nat. Mus._, 358, 359.