But the most common and rational Opinion is, that of the _Fœtus_ being form’d by the mixing of the two Seeds in the Womb; that Man and Woman are equally perfect; and that both of them being furnish’d with Testicles, which make a secretion of Seed, both of them must supply; and a Woman cannot be got with Child, unless she and the Man ejaculate their Seed at the same time. Those enclining to believe, that the Male Seed is sufficient of it self to form a _Fœtus_, plead that the Seed of a Man differs vastly from that of a Woman: That the former is white, and of a thick consistence, compos’d of all the parts that are capable to form a Body; and that the latter is only a sharp and yellowish serosity, which cannot contribute any thing towards the form of the _Fœtus_. But this is esteem’d by other Persons a groundless fancy; for the Structure of a Woman’s Testicle is more admirable than that of a Man, which shews that the Seed separated by it, is of considerable use: And several Children have their Mothers Features and Humour, which demonstrates that the Father, to whom they oftentimes bear no resemblance, does not furnish all himself. Those Persons who pretend that the Woman’s Seed contains the first, and the true Model of the _Fœtus_, compare the Female Testicles to a bunch of Grapes, or a Bee-hive; consisting of Vesicles, each of which contains a little Animal, almost compleated in all its Parts, after the same manner as the Egg of a Fowl: And that Man’s Seed contributes to _Generation_, no otherwise than as it animates the Egg: But the Opinion which is generally receiv’d, is that both the Male and the Female Seed contain such Particles, as are qualify’d to form a Body and a Spirit capable of all the Motions perform’d by the Animal, from which they have Being; and that _Generation_ depends upon an exact mixture of the two Seeds. The Opinions relating to the matter whereof the Seed is compos’d, are no less various than those of the forming of the _Fœtus_; some Anatomists say, ’tis prepar’d by the concoction and conversion of Blood, effected in this manner. The Blood imported to the Testicles by four spermatick Vessels, two Arteries and two Veins: The Vein and Artery of the same side, having a mutual Communication, blend the arterious and venous Blood together; and this mixture of arterious and venous Blood boyl and convert into Seed by the peculiar faculty and virtue of the Organs of the Testicles: This was the Opinion of the Antients. Others say, that the Seed is a Juice imported by the Nerves to the Organs of _Generation_; and that it distills from the Brain to the Privities; that in the time of Ejaculation one may feel it trickling along the _Spina_ of the Back; that when the Adventure is over, the Animal is feeble and dejected through the great Dissipation of the Spirits that are hurry’d along with the Seed; and that the Seed is of the same colour with the animal juice of the Nerves.