This belief concerning the navel is sometimes preserved through the whole period of adolescence, especially in girls of the so-called educated class, who are too well-bred to discuss the matter with their married friends, and believe indeed that they are already sufficiently well informed.

At this age the belief may not be altogether harmless, in so far as it leads to the real gate of sex being left unguarded.

In Elsass where girls commonly believe, and are taught, that babies come through the navel, popular folk-tales are current (_Anthropophyteia_, vol.iii, p.

89) which represent the mistakes resulting from this belief as leading to the loss of virginity.
Freud, who believes that children give little credit to the stork fable and similar stories invented for their mystification, has made an interesting psychological investigation into the real theories which children themselves, as the result of observation and thought, reach concerning the sexual facts of life (S.Freud, "Ueber Infantile Sexualtheorien," _Sexual-Probleme_, Dec., 1908).
Such theories, he remarks, correspond to the brilliant, but defective hypotheses which primitive peoples arrive at concerning the nature and origin of the world.

There are three theories, which, as Freud quite truly concludes, are very commonly formed by children.