474 Ulisse Aldrovandi

performs its role in forming the parts; that is to say, since this faculty alone assigns shapes to every part, if it is undermined by a lack of heat, an imbalance of the spirits, or some other cause, it cannot imprint the appropriate and natural shape upon the part it is forming. This is why some fetuses are occasionally born without eyes. We can assert this with greater confidence because Aristotle wrote that the substance of the seed contains a specific heat suited to each part of the body, and fetuses are often born damaged by either an abundance or a deficiency of this heat. Consequently, in some fetuses, the form of the eyes is seen on the forehead due to a weakness of the faculty, which was unable to transmit the material for the eyes to its destined location.

Next, we must consider the softness of the fetus's matter. It is possible for a limb of the fetus to be damaged by a slight cause, especially by a more violent movement; thus, the offspring acquires a monstrous shape through no fault of the mother. It is true, however, that the blame for a monstrous fetus is sometimes shifted to the mother when a pregnant woman delights in dances, leaping, and other disordered movements. Because of the narrowness of the womb, such violent motion provides the occasion for a monstrous birth; we believe a boy born with split nostrils was produced in this way.

Furthermore, when the head of a human fetus appears with a hare-lip or resembles another beast, some immediately resort to the mixing of seeds and "nefarious Venus" as the proper cause. Others attribute this defect to monstrous parents. Still others derive the cause from some flaw or disease, since a human face is sometimes turned into the face of a Satyr by the force of an illness, as happens in Satyriasis and Elephantiasis—conditions about which physicians speak frequently. Some attribute the ugliness of such a face to a defect in nourishment or the nutritive faculty. Others shift the blame to the material principle of the fetuses, since a perverse disposition of the matter—or, according to Averroes, the "disobedience of matter"—can be the cause of many monsters of this kind.

Others do not overlook the possibility of the seed degenerating into an alien nature, as many animal parts are then produced in human fetuses. Finally, others call the primary cause of these monsters the weakness of the agent or the progenitor. However, in our case, we believe that the imagination possesses great power, for the phantasy of either parent can provide the cause for a monstrous fetus. Yet the woman is especially prone to this, not only because of the long duration of gestation in the womb but also because the imagination operates most intensely in women.

Moreover, even without any conscious awareness on the part of the parents, horrifying dreams may present themselves during rest; thus, enormous phantoms with various animal parts appear to the phantasy. Anyone wishing to know more about these matters should refer to the universal causes set forth in the Chapter on Causes. This is how a boy was born with a face deformed into the shape of a frog, and we believe the boy born with that mass of flesh near the back of his head resembling a tortoise was produced for the same reason. Through the parents' imagination—and especially the mother's intense imagination—the formative faculty is supplied with the occasion to shape various parts of different animals, such as a tortoise. It has been explained above that the same thing happens to beasts; Cornelius Gemma reported that a puppy was born with the head of a hawk from a pregnant dog due to terror.

Furthermore, the face of a fetus is disfigured by a multitude of eyes due to an abundance of the material destined for forming those parts, and because of the strength of the formative faculty—unless we prefer to assert that this effect should be attributed to the strength of the "separative faculty," which distributes the material dedicated to forming the eyes into four parts. From this, it follows that four small eyes, fashioned by the formative power, defile the face of the fetus.

Finally, regarding infants born without a neck: although they could originate from many causes, we nonetheless judged that this particular monstrous fetus of ours resulted from an abundance of matter and the narrowness of the womb. The fetus was composed of fleshy limbs and somewhat imitated the form of Bacchus. Therefore, the matter was so plentiful that, due to the narrowness of the womb, it could not dilate or grow lengthwise; for this reason, the monster’s head grew joined to its shoulders. This narrowness of the womb could be natural, or it could be acquired through ailments of the uterus, especially due to unnatural tumors,