Theses medicae de divina et admiranda hominis in utero formatione

and contained by the amnion membrane. For it is not very acrid, since the infant is nourished by sweet blood and abounds in much moisture, which blunts its acrimony.

LXII.
Arantius is a witness that no urachus the tube connecting the bladder and the navel is found in man that travels in the middle of the umbilical vessels to carry urine between the chorion and amnion: for he affirms that that cord which is seen is not at all hollow, but performs the duty of a ligament.

LXIII.
Feces, however, are reserved in the intestines themselves until birth. For the blood that is drawn from the uterine liver through the umbilical vein is carried to the trunk of the portal vein, which delivers it to the liver: from it, the vena cava draws the purer part and distributes it through the entire body: the thicker part is transmitted to the spleen, the thinner and more bilious to the gall bladder. What is left as excrement is carried through the mesenteric vessels to the intestines, from which whatever good remains, the intestines extract for themselves as nourishment: but what is completely useless, existing as a kind of dregs of the blood (which Aristotle calls hyponion dregs/sediment), is poured into the gaping intestines through the mouths of the veins.

LXIV.
Since the matter of sweat is very thin, it can be easily resolved and dispersed. Therefore, through the sweat that Galen in the first book On Seed says is contained by the amnion, the urine itself should be understood.

LXV.
The time of formation cannot be defined with certainty, since the manner is not the same for all conceptions, nor is the strength of the formative faculty the same. However, females attain the perfection of all parts more slowly than males: although, once brought into the light, they grow and mature more quickly.

LXVI.
Hippocrates, however, proves that the conformation of the female is completed in forty-two days, but that of the male in thirty days, or a little more or less, by the argument of the menstrual purging that observes the same number of days from childbirth.

LXVII.
Why sometimes a male and sometimes a female is generated is a cause that must be cast back onto the nature of the seed itself, which the fetus imitates. For the seed emitted by either parent is either weak or robust by its quality, and much or little by its quantity. If, therefore, both are strong, a male will be generated: if weak, a female. But if one is strong for the most part and the other weak, a different sex will also arise according to the ratio of the quantity.