This at all events is certain, that nothing whatever of the future fœtus is apparent on this day, save and except certain sanguineous lines, the punctum saliens, and those veins that all present themselves as emanating from a single trunk, (as this itself proceeds from the punctum saliens,) and are distributed in numerous branches over the whole of the colliquament or dissolved fluid. These vessels afterwards constitute the umbilical vessels, by means of which, distributed far and wide, the fœtus as it grows obtains its nourishment from the albumen and vitellus. You have a striking example of similar vessels and their branchings in the leaves of trees, the whole of the veins of which arise from the peduncle or foot-stalk, and from a single trunk are distributed to the rest of the leaf.
The entire including membrane of the colliquament traversed by blood-vessels, corresponds in form and dimensions with the two wings of a moth; and this, in fact, is the membrane which Aristotle[178] describes as “possessing sanguineous fibres, and at the same time containing a limpid fluid, proceeding from those mouths of the veins.”
Towards the end of the fourth day, and the beginning of the fifth, the blood-red point, increased into a small and most delicate vesicle, is perceived to contain blood in its interior, which it propels by its contractions, and receives anew during its diastoles.
Up to this point I have not been able to perceive any difference in the vessels: the arteries are not distinguished from the veins, either by their coats or their pulsations. I am therefore of opinion, that all the vessels may be spoken of indifferently under the name of veins, or, adopting Aristotle’s[179] term, of venous canals.
“The punctum saliens,” says Aristotle, “is already possessed of spontaneous motion, like an animal.” Because an animal is distinguished from that which is none, by the possession of sense and motion. When this point begins to move for the first time, consequently, we say well that it has assumed an animal nature; the egg, originally imbued with a vegetative soul, now becomes endowed in addition with a motive and sensitive force; from the vegetable it passes into the animal; and at the same time the living principle, which fashions the chick from the egg, and afterwards gives it the measure of intelligence it manifests, enters into the embryo. For, from the actions or manifestations, The Philosopher[180] concludes demonstratively, that the faculties or powers of acting are inherent, and through these the cause and principle of life, the soul, to wit, and the actions, inasmuch as manifestation is action.