_Macrobius_ indeed gives us another account of this Custom, and that is from the Property which all Serpents have of casting their _Exuviæ_, or Upper-Skin, every Year, which makes ’em fit Emblems or Representations of Health; the Recovery of which from Sickness and Diseases may justly be looked upon as the beginning of a fresh Period of Life, and (as the throwing off the _Senectus_ of these Creatures seems to be) the Renewing of Age (9). Whether one or the other of these Reasons be allow’d of, or both thought good, certain it is that such fond and superstitious Fancies concerning the Viper, together with the mistaken Opinion that few of its Parts were exempt from Poison, did not suffer the Ancients to make any Curious Enquiries into its Nature by Anatomy and Experiments, and this is the Cause of the many Errors they have delivered down to us in these Points, which by gradual Advances have since been rectified, and the inward Make, Properties, and Generation of this Animal, largely treated of; more especially M. _Redi_ (10), _Charas_ (11), and Dr. _Tyson_ in his Dissection of the _Rattle-Snake_ (12), which is a larger Species of a Viper, have taken Pains on this Subject, to whose Discoveries, what is yet wanting, we shall add at the End of this Essay. The Symptoms which follow upon the Bite of a Viper, when it fastens either one or both its greater Teeth in any Part of the Body, are an acute Pain in the Place Wounded, with a Swelling at first Red, but afterwards Livid, which by degrees spreads farther to the Neighbouring Parts with great Faintness, and a Quick, tho’ Low, and sometimes Interrupted Pulse, great Sickness at the Stomach, with Bilious, Convulsive Vomitings, Cold Sweats, and sometimes Pains about the Navel; and if the Cure be not speedy, Death it self, unless the Strength of Nature prove sufficient to overcome these Disorders; and tho’ it does, the Swelling still continues inflamed for some time; nay, in some Cases more considerably upon the abating of the other Symptoms, than at the beginning; and often from the small Wound runs a sanious Liquor, and little Pustules are raised about it; the colour of the whole Skin is changed Yellow, as if the Patient had the _Jaundice_. These Mischiefs, altho’ different Climates, Season of the Year more or less Hot, the greater or lesser Rage of the Viper, the Beast it self of a larger or smaller Size, and consequently able to communicate more or less Venom, and the like Circumstances, may variously heighten or abate ’em, yet do usually discover themselves much after the same manner in all; unless the Bite happen not to be accompanied with the Effusion of that _Liquor_, which is the main Instrument and Cause of this violent and shocking Disturbance.