Page:Philosophical Transactions - Volume 003.djvu/211



He Author in the former of these Tracts, having first given an account, how the Air by its Elastick force is inspired, and upon the dilatation of the Chest, caused by the intercostal Muscles, drawn upwards, rushes into the Lungs, which are thereby expanded, being nothing else but a Body made up of very thin little Membranes, in the form of innumerable small bladders, delivers his thoughts of the Use of Respiration, waving those opinions, that would have Respiration serve either to cool the heart, or to make the Bloud pass through the Lungs out of the right ventricle of the heart into the left, or to reduce the thicker venal blood into thinner and finer parts; and affirming, That there is something in the Air, absolutely necessary to life, which is conveyed into the Blood; which, whatever it be, being exhausted, the rest of the Air is made useless, and no more fit for Respiration. Where yet he doth not exclude this Life, That with the expelled Air, the vapors also, steaming out of the Blond, are thrown out together.

And inquiring, what that may be in the Air, so necessary to life, he conjectures, that 'tis the more subtile and nitrous particles, the Air abounds with, that are through the Lungs communicated to the Blond: And this Aereal Niter he makes so necessary to all life, that even the Plants themselves do not grow in that Earth, that is deprived thereof, which yet, being exposed to the Air, and afresh impregnated by that fertilizing salt, becomes fit again to nourish those Plants.

And considering futher, what part this Nitrous Air acts, and what operation it performs in the Animal Life, he is of opinion, that this Niter, mixt with the sulphureous parts of the Blond, causeth a due fermentation, which he will have raised, not only in the Heart alone, but immediately in the Pulmonary vessels, and afterwards in the Arteries no less than in the heart. Examining also the reason, why Death so suddenly ensues upon Respiration suppressed, the Blond being then not yet unfit for motion, he inquires yet after another Use of Respiration, which maketh it so very necessary to Life. And considering with himself, that the Life of Animals conflicts in the Distribution of the Animal spirits, for the supply of which is required the Pulsation of the heart, and the Afflux of the Blond to the Brain, it seems to him, that Respiration is highly necessary to the motion of the heart, forasmuch as the heart is one of the Muscles, the motion of every one of which absolutely requires this Aereal Niter, so that without the same, even the beating of the Heart cannot be performed. Rh