CHAP. VII. How the Infant exerciseth his vital Faculties.
THE Infant also liueth in the wombe farre otherwise then hee liueth after he is borne; for neither is the Chest distended and contracted, because hee * 1.1 draweth not his breath by his mouth, neither doth hee engender any vitall spirits because he draweth them from his Mother: neither lastly dooth hee neede the motion or worke of the Heart or the Lungs, but the heate of the perticular parts is cherished, preserued and refreshed onely by Transpiration and the pulsa∣tion of the Arteries.
This different life hath also a different structure, substance, and vse of the vitall organes, which because it hath not beene knowne to any of the Anatomists of this our age; albeit it was first of all discouered by Galen in his sixte and fifteenth Bookes of the Vse of Partes, though obscurely, we will endeuour to make it as manifest and plaine as possibly we can.
In the Basis of the heart, that is, in the broad end, there appeare foure notable vesselles, * 1.2 two in the right ventricle, the Hollow veine, and the Arteriall veine, and two in the lefte, the great Artery, and the venall Artery. The vse of these after we are borne is this. The * 1.3 Hollow veine which gapeth with a wide mouth into the heart, powreth the bloode into the right ventricle as it were into a wide Cisterne, there it is reboyled and attenuated as well for the generation of vitall spirits, as also for the nourishment of the Lungs. A parte therefore of it swetheth through the middle wall betwixt the ventricles into the left ventri∣cle. Another part is carried by the arteriall veine into the thin, rare, and spongy substance of the Lungs. The Venall Artery leadeth into the left Ventricle the aer which wee breath in, prepared before in the Lungs where it is mingled with the blood, of which permixtion the vitall spirits are generated. This spirite the heart driueth into the trunke, and so into * 1.4 branches of the great Artery. In the infant before birth all these things are otherwise, and afarre other vse is there of all the vessels.
For the hollow veine doth not poure this streame of blood into the right ventricle, be∣cause neither the Lungs stand in need of attenuated blood, being at that time all of thē red, thicke, and immooueable, neither is there any generation of vitall spirits. The venall arte∣ry leadeth not the aer into the left ventricle, because the infant doeth not breath by the mouth, but onely hath vse of Transpiration. The great Artery receiueth no vitall spirites from the heart, but by the vmbilicall arteries: and therefore the Arteriall veine dooth not the office of a veine but of an Arterie, for it carrieth onely vitall spirits, but no bloode. A∣gaine the venall artery doth the office of a veine, containing onely thick and hie coloured blood for the nourishment of the Lungs. But because there was no passage from the Hol∣low veine to the venall Artery, Nature ioyned these two vessels (which doe but touch one * 1.5 another) by a large and round hole through which the bloode hath free passage from the Hollow veine, to the venall Artery.
To this hole she hath also set a thin and cleare Membrane like a couer, which shoulde giue way to the blood rushing out of the Hollow vein, but should prohibit it for returning againe thereinto. As also that by means of this Membrane, the hole after birth when there is no more vse of it, might sooner bee souldered vp, hauing a principle of consolidation so neere and ready at hand. And because the arteriall veine and the great artery were distant a little space each from other, she hath ioyned them by a third pipe or Canale of the Na∣ture of an artery running aslope betweene them, that so the vital spirite might passe freely from the great artery into the arteriall veine.
This is that admirable vnion of the vessels of the heart in the infant vnborn, to wit, of the * 1.6 hollow veine with the venall artery, and of the great Artery with the arteriall veine; but the shutting vp and resiccation of these vessels within a few dayes after the birth, that is indeed beyond all admiration. For that large hole vvhereof vvee spake, is so closed that there re∣maineth no footsteps or signe of it. As for the third arteriall pipe or Canale, vvithin a fevv daies it vvithereth and shrinketh together, and at length it grovveth so small that no man would beleeue there vvere any such thing.