Union structurale et Alliance en Afrique Centrale Léon de Sousberghe Summarium. - The term structural union is applied here to all those husband-wife relations that may appear, starting from birth, between consanguineal kin. They include these unions which for such a long time and so inappropriately have been called “preferential”. These are only a particular case of structural unions brought to conclusion and effectually practised; the most common form is of course between cross cousins. The author shows that at least in the parts of Central Africa formerly administered by Belgium (the former Congo, now Zaire, Rwanda and Burundi), the husband-wife relation never appears between cross cousins unless the same relation also exists between grand-parents and grand-children ; an interdependence already noticed by SELIGMAN (1924) in East Africa. But SELIGMAN’s formulations must be reversed: it is not true that the husband-wife relation between grand parent and grand-child is always followed by cross cousin union. But it is a fact that cross cousin union will never be found except in combination with husband-wife relation between first and third generation ; both are the expression of the identity between first and third generation. - The structural character of the husband-wife relation between cross cousins is obvious from the material gathered in the tribes of the Great Lakes region. The union is often hardly practised or brought to conclusion. Nevertheless, cross cousins are husband and wife from birth and remain so till death, even after marriage with other partners. Even after marriage with others, the cross cousin may often consider himself in the house of his married cross cousin as “in his own home”, and can exercise authority, the actual or factual husband having to step aside and keep in the background while he is there. — If a wife has to be reprimanded (e.g. for her laziness), the actual husband will appeal to the cross cousin, the structural husband, and tell him: “our wife has such a shortcoming ; could you tell her”. The admonishment will be more readily accepted from the structural husband, the cross cousin. Reciprocally, the (female) cross cousin considers herself “at home” (i.e. in her home) in the house of her cross cousin, even after marriage with another man. She can go straight into the kitchen without asking permission, prepare a meal for herself, etc. The actual wife must keep in the background ; she cannot complain, but should show herself submissive and help fui. Relations between actual and structural husband or wife are said to be generally good and are an inter esting object of study. The cross cousin union is said to be particularly agreable to the ancestors and specially under their protection, to the point that they do not allow it to be dissolved among the Nyanga and Hunde. There is no marriage ceremony between cross cousins; they are already born husband and wife. But there is a divorce ceremony if a girl wants to marry another man than her cross cousin. - The same principle of identity of alternate generations is shown to govern the evolution of relations between in-laws. This evolution of relations between in-laws of different generations is actually common in the Great Lakes region, while still exceptional in the Lower Congo region. — Avoidance between mother-in-law and son-in- law is mitigated or ended when the son-in-law presents a son to his mother-in-law : “Here is K. JL Narr nmprn