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

by William Harvey

The brain presented itself as a large and soft coagulum, full of ample vessels. The ventricles of the heart were of equal capacity, and their walls of the same thickness. In the thorax, and covered by the ribs, three cavities, nearly of the same dimensions, were perceived; of these the lowest was occupied by the lungs, which are full of blood, and of the same colour as the liver and kidneys; the middle cavity was filled by the heart and pericardium; the superior cavity, again, was possessed by the gland called the thymus, which is now of very ample size.

In the stomach there was some chyle discovered, not very different in character from the fluid in which the embryo swam. It also contained some white curdled matter, not unlike the mucous sordes which the nurse washes particularly from between the folds of the skin of new-born infants. In the upper part of the intestines there was a small quantity of excrementitious or chylous matter; the lower bowels contained meconium. In the urinary bladder there was urine, and in the gall bladder bile. The intestinum cœcum, that appendix of the colon, was empty as in the adult, and apparently superfluous, not as in the lower animals—the hog, horse, hare, constituting as it were another stomach. The omentum, or apron, floated over the intestines at large like a thin and transparent veil or cloud.

The kidneys at this epoch are not yet formed into a smooth and continuous rounded mass, as in the adult, but are compacted of numerous smaller masses, as we see them in the calf and sturgeon, as if there were a renal globule or nipple placed at the extremity of each division of the ureter, from the orifice of which the urine distilled. Over the kidneys two bodies, first observed by Eustachius, are discovered, very abundantly supplied with blood, so that their veins, which anatomists designate as venæ adiposæ, are not much smaller than the emulgents themselves. The liver and spleen, according to their several proportions, are equally full of blood.

I may here observe, by the way, that in every strong and healthy human fœtus we everywhere discover milk; it is particularly abundant in the thymus gland, though it is also found in the pancreas, through the whole of the mesentery, and in certain lacteal veins and glands, as it seems, situated between the divisions of the mesenteric vessels. Moreover, it can be pressed and indeed sometimes flows spontaneously from the breasts of newly-bom infants, and nurses imagine that this is beneficial to the infant.

And it clearly appears that this fluid, which abounds in the ovum, is no excrementitious matter thrown off by the embryo, nothing like urine or sweat, because its relative quantity is diminished as the period of parturition approaches, when the fœtus is of course larger, and, as it consumes a greater quantity of nutriment, accumulates excrementitious matter more abundantly than it did in the first months of pregnancy. Let it be added, that the bladder is at this time distended with urine. For my own part I have never been able to discover that conduit for the urine, from the bladder to the umbilicus, which anatomists describe under the name of urachus; I have, on the contrary, frequently seen urine escaping by the penis, but never by any urachus, when the bladder was pressed upon with the hand.

So much for what I have observed with reference to the order of the parts in the development of the human fœtus.

In the fourth and last process the parts of the lowest state and order are produced, those, namely, that do not exist as needful to the being or to the maintenance of the individual, but only as defences against external injury, as ornaments, or as weapons of offence.

The outermost part of all, the skin, with its several appendages,—cuticle, hair, wool, feathers, scales, shells, claws, hooves, and other items of the same description, may be regarded as the principal means of defence or protection. And it is well devised by nature, who, indeed, never does aught amiss, that these parts are the last to be engendered, inasmuch as they could never be of use or avail as defences until the animal was born. The common domestic pullet is therefore born covered with down only, not with feathers, like certain other birds which have to be speedily prepared for flight, because it has to seek its food on foot, not on the wing, and by active running about hither and thither. In like manner the young of ducks and geese, which feed swimming, have their feathers and wings perfected at a later period than their feet and legs. It is otherwise with swallows, however, which have to fly sooner than to walk, because they feed on the wing.

The down of the pullet begins to appear after the fourteenth day, the fœtus being already perfect in all its parts. When the feathers first show themselves, they are in the guise of points within the skin, but by and by the feathers project, like plants from the ground, increase in length, become unfolded, invest the whole body, and protect it against the inclemencies of the atmosphere.

Feathers differ from quills in form, use, place of growth, and order of production. The pullet is feathered before it has any quills, for the quill-feathers only grow in the wings and tail, and also spring more deeply, from the very lowest part of the integument, or even from the periosteum, and serve essentially as instruments of motion; the feathers again arise superficially from the skin, and are everywhere present as means of protection.