Finally, he [sc. Aveling] believes that menstruation is probably determined by the act of “denidation,” as he calls it, because it is from the denided surface that the menstrual flow comes.
denidation — Exfoliation of the superficial portion of the mucous membrane of the uterus; stripping off of the menstrual decidua. [L. de, from, + nidus, nest] * * * den·i·da·tion .den ə dā shən … Medical dictionary
denidation — … Useful english dictionary