Now if we likewise consider the exceeding Smallness of the Pulmonary Vessels, and also that the whole Quantity of Blood in the Body must necessarily pass this Organ, in order to its being attenuated and made fit for Circulation; It will necessarily follow, that the Alterations made in the Texture of the Blood by the Poisonous _Effluvia_, are communicated to it chiefly thro' this Organ. Besides, the Poisonous Particles do not only Enter into the Blood in greater Quantities in this Bowel, but when carried by these Passages, are capable of doing much more Mischief, than if entring in at any other Part of the Body, in Regard that they are more intimately mixt with it in its Comminution. I have insisted the more largely on this Argument, because I find that most who have wrote in this Subject, tho' they do suppose some of the Contagious Particles may be communicated to the Blood this way, yet lay the greatest Stress on the Mixture of these Particles with the _Saliva_, which being swallowed carries them in common with our Nourishment. 'Tis not Improbable indeed, that many of these Particles may be this way communicated to the Blood; but it is as Probable, that many of them which are by this way Communicated, lose much of their Force by their Mixture with the _Bile_ and other Juices; As we see happens in the Poison of the _Viper_, which taken at the Mouth is not deadly, but when mixed immediately with the Blood produces the most violent Symptoms. The same may be observed from many other Substances, which may be safely taken into the Body by the common Passages, as most Acids, Spirit of Wine, and other Substances, but when mixed immediately with the Blood, by Injections into the Vessels of living Animals, produce Coagulations, Convulsions, and Death: The principal Reason which has induced Physicians to suppose, that the Poisonous _Effluvia_ are chiefly communicated by these Passages, are those violent Vomitings which frequently accompany it; But this happens equally in many other Fevers, where there cannot be the least Suspicion of Contagion. The only Objection to what I have here advanced seems to be, That if the Contagion was communicated to the Blood chiefly by the Lungs, the Coagulations wou'd be immediately form'd there, and this Bowel totally obstructed. But if we consider, that the Chief Application of the Air to the Pulmonary Vesicles is in Expiration, immediately after which the Blood enters the _Vena Arteriosa_, whose Branches continually grow wider, and give Space and Time for the Coagulating Particles to act with their full Force, this Objection will of it self fall to the Ground.