Having seen the second process or preparation of the egg, towards the production of the 밤의전쟁 embryo which presents itself in{235} the course of the third day, we proceed to the Third Stage, which falls to be considered after the lapse of three days and as many nights. Aristotle[176] says: “Traces of generation commence in the egg of the hen after three days and three nights [of incubation];” for example, on Monday morning, if in the morning of the preceding Friday the egg has been put under the hen. This stage forms the subject of the third figure in Fabricius.

If the inspection of the egg be made on the fourth day, the metamorphosis is still greater, and the change likewise more wonderful and manifest with every hour in the course of the day. It is in this interval that the transition is made in the egg from the life of the plant to the life of the animal. For now the margin of the diffluent fluid looks red, and is purpurescent with a sanguineous line, and nearly in its centre there appears a leaping point, of the colour of blood, so small that at one moment, when it contracts, it almost entirely escapes the eye, and again, when it dilates, it shows like the smallest spark of fire. Such at the outset is animal life, which the plastic force of nature puts in motion from the most insignificant beginnings!

The above particulars you may perceive towards the close of the third day, with very great attention, and under favour of a bright light (as of the sun), or with the assistance of a magnifying glass. Without these aids you would strain your eyes in vain, so slender is the purple line, so slight is the motion of the palpitating point. But at the beginning of the fourth day you may readily, and at its close most readily, perceive the “palpitating bloody point, which already moves,” says Aristotle, “like an animal, in the transparent liquid (which I call colliquamentum); and from this point two vascular branches proceed, full of blood, in a winding course” into the purpurescent circle and the investing membrane of the resolved liquid; distributing in their progress numerous fibrous offshoots, which all proceed from one original, like the branches and twigs of a tree from the same stem. Within the entering angle of this root, and in the middle of the resolved liquid, is placed the red palpitating point, which keeps order and rhythm in its pulsations, composed of [alternate] systoles and diastoles. In the diastole, when it has{236} imbibed a larger quantity of blood, it becomes enlarged, and starts into view; in the systole, however, subsiding instantaneously as if convulsed by the stroke, and expelling the blood, it vanishes from view.

Fabricius depicts this palpitating point in his third figure; and mistakes it—a thing which is extraordinary—for the body of the embryo; as if he had never seen it leaping or pulsating, or had not understood, or had entirely forgotten the passage in Aristotle. A still greater subject of amazement, however, is his total want of solicitude about his chalazæ all this while, although he had declared the rudiments of the embryo to be derived from them.

Ulyssus Aldrovandus,[177] writing from Bologna nearly at the same time, says: “There appears in the albumen, as it were, a minute palpitating point, which The Philosopher declares to be the heart. And I have unquestionably seen a venous trunk arising from this, from which two other branches proceeded; these are the blood-vessels, which he says extend to either investing membrane of the yelk and white. And I am myself entirely of his opinion, and believe these to be veins, and pulsatile, and to contain a purer kind of blood, adapted to the production of the principal parts of the body, the liver, to wit, the lungs, and others of the same description.” Both of the vessels in question, however, are not veins, neither do they both pulsate; but one of them is an artery, another a vein, as we shall see by and by, when we shall farther show that these passages constitute the umbilical vessels of the embryo.

Volcher Coiter has these words: “The sanguineous point or globule, which was formerly found in the yelk, is now observed more in the albumen, and pulsates distinctly.” He says, erroneously, “formerly found in the yelk;” for the point discovered in the vitellus is white, and does not pulsate; nor does the sanguineous point or globe appear to pulsate at the end of the second day of incubation. But the point which we have indicated in the middle of the circle, and as constituting its centre in connexion with the vitellus, disappears before that point which is characterized by Aristotle as palpitating, can be discerned; or, as I conceive, having turned red, begins to pulsate. For{237} both points are situated in the centre of the resolved fluid, and near the root of the veins which thence arise; but they are never seen simultaneously: in the place of the white point there appears a red and palpitating point.

That portion of Coiter’s sentence, however, where he says: “the punctus saliens is now seen in the albumen rather than in the yelk,” is perfectly accurate. And, indeed, moved by these words, I have inquired whether the white point in question is turned into the blood-red point, inasmuch as both are nearly of the same size, and both make their appearance in the same situation. And I have, indeed, occasionally found an extremely delicate bright purple circle ending near the ruddy horizon surrounding the resolved liquid, in the centre of which there was the white point, but not the red and pulsating point apparent; for I have never observed these two points at one and the same time. It were certainly of great moment to determine: Whether or not the blood was extant before the pulse? and whether the pulsating point arose from the veins, or the veins from the pulsating point?

So far as my observations enable me to conclude, the blood has seemed to go before the pulse. This conclusion is supported by the following instance: on Wednesday evening I set three hen’s eggs, and on Saturday evening, somewhat before the same hour, I found these eggs cold, as if forsaken by the hen: having opened one of them, notwithstanding, I found the rudiments of an embryo, viz., a red and sanguinolent line in the circumference; and in the centre, instead of a pulsating point, a white and bloodless point. By this indication I saw that the hen had left her nest no long time before; wherefore, catching her, and shutting her up in a box, I kept her upon the two remaining eggs, and several others, through the ensuing night. Next morning, very early, both of the eggs with which the experiment was begun, had revived, and in the centre there was the pulsating point, much smaller than the white point, from which, like a spark darting from a cloud, it made its appearance in the diastole; it seemed to me, therefore, that the red point emanated from the white point; that the punctum saliens was in some way engendered in that white point; that the punctum saliens, the blood being already extant, was either originally there produced, or there began to move. I have, indeed, repeatedly seen the{238} punctum saliens when all but dead, and no longer giving any signs of motion, recover its pulsatile movements under the influence of renewed warmth. In the order of generation, then, I conceive that the punctum and the blood first exist, and that pulsation only occurs subsequently.