Duden 113: "To us, biological or physiological conditions are unique and specific as to sex and age [...] We understand the biological essentially in an anatomical and physiological materiality, linked to specific bodily phenomena depending on gender and age. The doctor from Eisenach attests for himself and his female patients the opposite view, which we also know from the scholarly literature of his time"
from these texts "we can get an idea about the physiological difference between women and men. The astonishing finding is that the factors shaping the characteristics of the female body were only tenuously related to what we know as 'sex characteristics' [...] Many of the manifestations that we clearly perceive as sex characteristics, were in the seventeenth and eighteenth centuries not unequivocal signs for the difference between man and woman [...] The eye of culture sees in the order of nature what it expects to see"
"blood in every form was central to all reflections about the diseases of women, but it was not in itself a necessary element of what gave them their special gender-characteristic"
114: "monthly bleeding was not an exclusive mark of grown women, [and] it was also not a mark of their esse, their being-a-woman"
115: "a spontaneous issue of blood was also observed in men. Evidently the discharged matter itself was not gender-specific" (see, for instance, the "bleeding piles," considered "analogous to women's 'monthlies'--a means of discharging "superfluous humors")