[Experimental testing of Pflüger's reflex hypothesis of menstruation in late 19th century]. / Experimentelle Prüfungen der Pfügerschen Reflexhypothese der Menstruation im späten 19. Jahrhundert.

Pflüger's hypothesis of a nerve reflex as the cause of menstruation published in 1865 and accepted by many, nonetheless did not lead to experimental investigations for 25 years. According to this hypothesis the nerve reflex starts in the ovary by an increase of the intraovarian pressure by the growing follicles. In 1884 Adolph Kehrer proposed a program to test the nerve reflex, but only in 1890, Cohnstein artificially increased the intraovarian pressure in women by bimanual compression from the outside and the vagina. His results were not convincing. Six years later, Strassmann injected fluids into ovaries of animals and obtained changes in the uterus resembling those of oestrus. His results seemed to verify a prognosis derived from Pflüger's hypothesis. Thus, after a long interval, that hypothesis had become a paradigma. Though reasons can be given for the delay, it is little understood, why experimental testing started so late.

[Bilateral oophorectomy in the woman in late 19th century. Methodological value of castration for discovery of ovarian hormones]. / Bilaterale Oophorektomie der Frau im späten 19. Jahrhundert. Zum methodologischen Wert der Kastration für die Entdekkung ovarieller Hormone.

In 1872, the castration of women was introduced as a therapeutic procedure. The ovaries were mainly removed because of nervous and mental diseases, uterine fibromyomata with menorrhagia, osteomalacia and carcinoma of the breast. These partially successful operations led to various hypotheses on the mechanism of ovarian action. It was only in 1895 that the cessation of hormonal production was assumed to be responsible for the effects of ovarian removal. The hypothesis of an internal secretion of the ovaries was eventually clearly supported by animal experiments around 1900.

[On the beginnings of hormonal contraception (author's transl)]. / Zur Geschichte der hormonalen Empfängnisverhütung

The possibility of hormonal contraception was postulated as early as 1919 by the physiologist Ludwig Haberlandt in Innsbruck. The same year, he began to test his hypothesis in animal experiments. In 1924 he succeeded in his efforts to render mice infertil by orally administering ovarian and placental extracts. He failed to have his method tried in women.