the Blood in a Fœtus.
Those that contend for the conveyance of the Nutricious Juice, through the Umbilical Vein from the Placenta, are forc'd upon two Difficulties next to Absurdities. For first they are oblig'd to make this Vein, which, as all other Veins, seems dedicated to the Re-conveyance of Blood only, the proper and immediate Chanel, thro' which a very different Liquour is to be carried; and next, to give a Power of Attraction or Suction to it; because the Nutricious Juice, which it is thus destin'd to carry, is both viscous and stagnant, and has neither force to drive, nor subtilty to penetrate, or insinuate it self into the Capillary Veins; and therefore must be drawn or suck'd as Milk is from the Breast, to which the Placenta and its Nutricious Juice are by the Favourers of them expresly compar'd. But if this were the sole use of the Placenta, and Umbilical Vessels, why were the Umbilical Arteries sent along with the Vein? Their business is not to bring any thing back to the Fœtus, nor can they contribute any thing to the benefit of the Mother; for the Uterine Arteries bring all to the Placenta, the Umbilical Vein carries it to the Fœtus, and the Uterine Veins convey
back again the Surcharge of the Mother's Blood; the Umbilical Arteries only, have nothing to do, and are superfluous and impertinent, which is contrary to the constant Practice of Nature. Yet if Autopsie did in the least countenance this Hypothesis, some Defence might still be made; but we find in the Umbilical Vein of a Fœtus nothing but Florid Blood, such as in all probability it received immediately from the Arteries of the Mother without any mixture. And therefore I can't help concluding, that this Opinion engages its Favourers in some Absurdity, without Necessity and without Proof.
They that from the Placenta supply the Body of the Fœtus with Air , are as