sisters boast about grand accomplishments, the youngest about giving birth to wondrous children; the king marries her and makes her his queen; the elder sisters replace their nephews for animals, and the queen is cast in the sea with her son in a barrel; mother and son survive and the son goes after strange and miraculous items; at the end of the tale, the deceit is revealed and the queen's sisters are punished. French scholar Gédeon Huet considered this format as "the Slavic version" of Les soeurs jalouses and suggested that this format "penetrated into Siberia", brought by Russian migrants. Russian tale collections attest to the presence of Baba Yaga, the witch of Slavic folklore, as the antagonist in many of the stories. Russian scholar T. V. Zueva suggests that this format must have developed during the period of the Kievan Rus, a period where an intense fluvial trade network developed, since this "East Slavic format" emphasizes the presence of foreign merchants and traders. She also argues for the presence of the strange island full of marvels as another element. Rescue of brothers from transformation In some variants of this format, the castaway boy sets a trap to rescue his brothers and release them from a transformation curse. For example, in (""), a Hungarian variant, when the hero of the tale sees a flock of eleven swans flying, he recognizes them as their brothers, who have been transformed into birds due to divine intervention by Christ and St. Peter. In another format, the boy asks his mother to prepare a meal with her "breast milk" and prepares to invade his brothers' residence to confirm if they are indeed his siblings. This plot happens in a Finnish variant, from Ingermanland, collected in (, or "Brother and Sister, and the golden-haired sons of the King"). The mother gives birth to six sons with special traits who are sold to a devil by the old midwife. Some time later, their youngest brother enters the devil's residence and succeeds in rescuing his siblings. Russian scholar T. V. Zueva argues that the use of "mother's milk" or "breast milk" as the key to the reversal of the transformation can be explained by the ancient belief that it has curse-breaking properties. Likewise, scholarship points to an old belief connecting breastmilk and "natal blood", as observed in the works of Aristotle and Galen. Thus, the use of