But before I proceed to enquire into the Nature and Manner of Acting of this _Juice_, it may be worth the while to take Notice, that this is not made on purpose to be deadly and destructive to _Mankind_; but that the true Design of it is (tho’ Authors have not regarded it) to perform an Office and Service of so great Moment, to the Preservation of the Individual, that without it this Creature could not subsist. For Vipers live chiefly upon Lizzards, Frogs, Toads, Mice, Moles, and the like Animals, which they do not chew, but swallow down whole, and they lie in the Stomach; or if that be not big enough to receive them, partly in that, and partly in the Œsophagus, which is membranous and capable of great Distension, till by the Salival Juices of those Parts, together with the Help of the Fibres of the Stomach, and the Contraction of the Muscles of the Abdomen, they are gradually dissolved into a Fluid Substance, fit for the Nourishment of their Bodies, which is the Work of many Days; this is _one_ Reason why these Creatures can live so long without taking any fresh Food, which I have known them to do Three or Four Months; as _another_ is, that their Blood is a grosser and more viscid Fluid than that of most other Animals; so that there is but a very little expence of it by Transpiration, and consequently less need of Recruit; this not only _Microscopes_ discover, but Reason teaches; because there is but very little Muscular Force in the Stomach to comminute the Food, and make a Chyle of fine Parts, and therefore the Blood must accordingly be of a Tough and Clammy Consistence. Besides, the Heart of a Viper has properly but one Ventricle, and the Circulation of the Blood is performed after the same Manner as it is in a Frog and Tortoise, in which not above one Third of it passes thro’ the Lungs; upon which Account its Comminution in them by the Air is proportionably lesser than in other Animals. Now such a manner of Feeding as _this_ does necessarily require, that the Prey should upon the first Catching be immediately kill’d, otherwise it were by no means fit to be let into the Stomach; for we are not to think that the Force of this Part would be alone sufficient to destroy it, the Subtilty of a living Creature (besides the Consideration of the Weakness of the Fibres) being in a great Measure able to elude _that_, as indeed we do every Day find live Animals in the Ventricles of others; and therefore to do _this_ is the proper Use both of the Teeth and their Poison; for which being designed and adapted, it is no wonder if the Viper, this same Way by which it destroys its Prey, proves sometimes mischievous to any other Creatures besides, when it happens to be enraged, or by any Provocation stirr’d up to bite.