The Works of William Harvey M.D. / Translated from the Latin with a life of the author

by William Harvey

EXERCISE THE THIRD.

Of the upper part of the hen’s uterus, or the ovary.

The uterus of the fowl is divided by Fabricius into the superior and inferior portions, and the superior portion he calls the ovary.

The ovary is situated immediately beneath the liver, close to the spine, over the descending aorta. In this situation, in the larger animals with red blood, the cœliac artery enters the mesentery, at the origin, namely, of the emulgent veins, or a little lower; in the situation moreover in which in the other red-blooded and viviparous animals the vasa præparantia, tending to the testes, take their origin: in the same place at which the testes of the cock-bird are situated, there is the ovary of the hen discovered. For some animals carry their testicles externally; others have them within the body, in the loins, in the space midway from the origins of the vasa præparantia. But the cock has his testicles at the very origin of these vessels, as if his spermatic fluid needed no preparation.

Aristotle[131] says that the ovum begins at the diaphragm; “I, however,” says Fabricius, “in my treatise on Respiration, have denied that the feathered kinds have any diaphragm. The difficulty is resolved by admitting that birds are not entirely destitute of a kind of diaphragm, inasmuch as they have a delicate membrane in the place of this septum, which Aristotle calls a cincture and septum. Still they have no diaphragm that is muscular, and that might aid respiration, like other animals. But, indeed, Aristotle did not know the muscles.”

Thus is the prince of philosophers accused and excused in the same breath, his challenger being himself not free from error; because it is certain that Aristotle both knew the muscles, as I have elsewhere shown, and the membranes, which in birds are not only situated transversely in the direction of the cincture of the body, but extended in the line of the longitudinal direction of the belly, supplying the place of the diaphragm [of quadrupeds] and being subservient to respiration, as I have shown in the clearest manner in my disquisitions on the Respiration of Animals. And, passing over other particulars at this time, I shall only direct attention to the fact, that birds breathe with great freedom, and in singing also modulate their voice in the most admirable manner, their lungs all the while being so closely connected with their sides and ribs, that they can neither be dilated and rise, nor suffer contraction in any considerable degree.

The bronchia or ends of the trachea in birds, moreover, are perforate, and open into the abdomen (and this is an observation which I do not remember to have met with elsewhere), so that the air inspired is received into and stored up within the cells or cavities formed by the membranes mentioned above. In the same manner as fishes and serpents draw air into ample bladders situated in the abdomen, and there store it up, by which they are thought to swim more lightly; and as frogs and toads, when in the height of summer they respire more vigorously assume more than the usual quantity of air into their vesicular lungs, (whence they acquire so large a size,) which they afterwards freely expire, croaking all the while; so in the feathered tribes are the lungs rather the route and passage for respiration than its adequate instrument.

Now, had Fabricius seen this, he would never have denied that these membranes (with the assistance of the abdominal muscles at all events,) could subserve respiration and perform the office of the diaphragm, which, indeed, of itself, and without the assistance of the abdominal muscles, were incompetent to act as an instrument of respiration. And, then, the diaphragm has another duty to perform in those creatures in whom it is muscular or fleshy, viz., to depress the stomach filled with food, and the intestines distended with flatus, so that the heart and lungs shall not be invaded, and life itself oppressed in its citadel. But as there was no danger of anything of this kind in birds, they have a membranous septum, perfectly well adapted to the purposes of respiration, so that they have very properly been said to have a diaphragm. And were birds even entirely without anything in the shape of a diaphragm, still would Aristotle not be liable to criticism for speaking of the ova commencing at the septum transversum, because by this title he merely indicates the place where the diaphragm is usually met with in other animals. In the same way we ourselves say that the ovary is situated at the origin of the spermatic vasa præparantia, although the hen has, in fact, no such vessels.

The perforations of the lungs discovered by me (and to which I merely direct attention in this place,) are neither obscure nor doubtful, but, in birds especially, sufficiently conspicuous, so that in the ostrich I found many conduits which readily admitted the points of my fingers. In the turkey, fowl, and, indeed, almost all birds, you will find that a probe passed downwards by the trachea makes its way out of the lungs, and is discovered lying naked and exposed in one or another of the abdominal cells. Air blown into the lungs of these creatures with a pair of bellows passes on with a certain force even into the most inferior of these cells.

We may even be permitted to ask, whether in man, whilst he lives, there is not a passage from openings of the same kind into the cavity of the thorax? For how else should the pus poured out in empyema and the blood extravasated in pleurisy make its escape? In penetrating wounds of the chest, the lungs themselves being uninjured, air often escapes by the wound; or liquids thrown into the cavity of the thorax, are discharged with the expectoration. But our views of this subject will be found fully expressed elsewhere, viz., in our disquisitions on the Causes, Uses, and Organs of Respiration.