Among the Sonthals also, an aboriginal tribe of India, whose marriages are celebrated simultaneously once a year, the candidates for marriage must first live six days together, and it is only after this trial that it is lawful for them to marry.[155] With certain Tartar tribes of Russia in Europe and of Siberia there existed an institution of experimental marriages lasting for a year, if the woman did not become a mother during that period.[156] In the island of Ceylon, according to Davy, there are also provisional marriages, confirmed or annulled at the end of a fortnight.[157] Among the Jews in Morocco the Rabbis consecrate temporary marriages, for three or six months, according to agreement. The man only engages to acknowledge the child if needful, and to make a certain donation to the mother.[158] Strabo tells us of an analogous custom prevailing in antiquity among the Tapyres (Parthians), according to which a woman, after having had two or three children by a man, was forced by law to change her husband.[159] This is almost exactly what Marshal Saxe demanded for Frenchwomen in the last century. We must not confound these experimental marriages, which are regulated, and in some sort legal, with free and easily cancelled unions still more common, as, for example, those of the Nouka-Hivians, that are broken at will, provided there are no children;[160] those of the Hottentots;[161] those of the Abyssinians, who marry, part, and re-marry at will.[162] These last unions, founded merely on individual caprice, have nothing extraordinary about them, and we know that they are not rare in civilised countries. Much more curious, from a point of view of sexual and conjugal morality, are the partial marriages, which only bind the parties for certain days of the week. This is a rare kind of marriage that seems improbable to us, yet it has been proved to have existed among the Hassinyehs of the White Nile, of Arab or perhaps Berber race. By an agreement, which is sharply discussed beforehand, the Hassinyeh woman engages to be a faithful wife for a fixed number of days in the week, generally three or four, but this is in proportion to the number of heads of cattle given to the parents by the bridegroom as the price of their daughter, and it is the mother herself who makes the bargain. Naturally, on the days that are not reserved the woman is free, and she has a right to use her liberty as she pleases.[163]