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OF FEAVERS.
CHAP. I. The Anatomy of the Blood; and its Resolution into five Principles: A comparing it with Wine and Milk.
THE Doctrine of Fermentation being explicated, it remains that we handle the chief Instance or Example of it, to wit, Feavers. For it seems that a Feaver is only a Fermentation, or immoderate Heat, brought into the Blood and Humors. Its Name is derived from Februo (or Pur∣gament, which also is derived from Ferveo, to be Hot) which Word indeed is commodiously put to every Feaver; for that the Blood in this Disease grows hot; and besides, by its fervor, as working must, it is purged from its filthinesses. But that this Fermentation or feaverish Effervency may be rightly explicated, these three things are to be con∣sidered. First, What the fermenting Liquor is; whether only Blood, or any humors besides. Secondly, In what Principles in the mixture, and in what proportion of them this Liquor consists. Thirdly, and lastly, By what motion and turgescency of those Parts or Particles, of which the Blood is made, the Feaverish Effervescency is stirred up. These be∣ing thus premised, the Doctrine of Feavers shall be delivered, not from the Opinions of others, but according to the comparisons of Reasons, picked (though from ours, yet) from diligent and frequent Observation, and confirmed by certain Experiments; all which however, I willing∣ly submit to the Judgment of the more skilful.
It plainly appears, even to the Sense, that the Blood doth hugely boil up, and rage in a Fea∣ver; for every one (though rude and unskilful) being in a Feaver, complains of the Blood be∣ing distempered, and of the same growing hot in the Vessels, and as it were, put into a fury. Al∣so, besides the Blood raging in the Veins and Arteries, it may be lawfully suspected, that that Juice with which the Brain and Nervous Parts are watered, is wont oftentimes to be in fault; for when this Liquor is seen to be carried back from the Blood, into the nervous stock by a con∣stant motion, and certain Circulation, and from thence through the Lymphatick Vessels, into the bosom of the Blood, it is probable, if by reason of a Taint contracted from the Blood, that humor be depraved in its disposition, or is perverted from its equal motion, that from thence the Rigour, and Pain, Convulsion, Delirium, Phrensie, and many more Symptoms of the Nervous kind, usual in Feavers do arise.
After the Blood and Nervous Liquor, two other Humors, for that being apt to grow hot, fall into our consideration, viz. The Chyme or nourishing Juice, continually coming to the Mass of Blood, and the serous Latex, perpetually departing from the same, which, though they be the first and last Liquors separated from the Blood, and distinct from it, yet being con∣fused with it, they ought to be esteemed as its associate parts or complements; for the nourish∣able Juice being fresh brought, is accounted the crude part of the Bloud, and to be assimilated; and the Serum, it's stale part, and to be carried away. And after this manner, so long as either are circulated with the Bloud it self, in the Vessels they participate of the heats of the first begot∣ten Bloud, and oftentimes occasionally begin them, or increase them being begun; but by what means these things come to be be done, is declared hereafter in their proper places. As to the rest of Humors, which are only the Recrements of the nutricious Juice, or the bloud, when they are included, either in their proper Receptacles, or constrained in the narrow spaces in the Viscera, neither wash the several parts of the Body with a continual lustration, as the Bloud or Nervous Liquor, or the other Humors but now recited, are to be exempted from this Rank; sometimes perhaps they may be the occasional Cause that the Bloud doth conceive an undue Effervency, or that it persists in it longer; but it is only the Bloud, (with the the Nervous Liquor, the alible Juice, and Serum Associates)