There is no Cochlea in the Ear of the Viper; but the Anterior Demicircular Canal opens into a Semicanal, which makes some Spiral Turns in the Fore-part of the Labyrinth; in like manner as it is in Fish.
The Passage for the Air to these Organs is not Outward, but, as in some Fish, thro’ the Mouth, between the Upper and Under Jaws, running below the Second of the Common Bones. But of This, and also of the True Mechanic Use of the aforesaid Parts, more hereafter.
Poisonous Animals.
As the Viper is Hurtful by Instilling a Liquid Poison into the Wound made by its Teeth; so likewise are all Venomous Creatures whatsoever, whether they Bite or Sting, tho’ there be some difference in the Contrivance of their Organs, Mischievous after much the same Manner; and mostly for the same good Use and Purpose, that is, in order to Kill their Prey.
This will fully appear, by Examining the Instruments of Death in several of Them.
First then, The Spider which lives upon Flies, Wasps, and the like Insects, is provided with a hooked Forceps, placed just by the Mouth, very sharp and fine; with this he pierces the Flesh of little Creatures caught in his Webb, and at the same time infuses a Juice into the Puncture, by which means the Animal being Killed, He sucks out the Moisture from the Body, and leaves it a dry husky Carkass.
Mr Van Leewenhoek, in his Account of Spiders, lately publish’d [(38)], has, together with the other Parts, by the help of his Glasses, describ’d these Weapons, which He finds to lie couched on each side the Mouth, in a Row of Teeth, till they are raised to do Execution. These Rows of Small Teeth are design’d to hold the Prey, that It may not escape the Force of the Bite. And in the Convex Part, towards the Point of each Claw, He has delineated a little Aperture or Slit, thro’ which he supposes the Poison issues out at the same time the Wound is made.
This Situation and Motion of these Parts, I have several times view’d; but was never able to discern the Exit or Opening; which, having a just Deference to the Industry and Application of so Nice an Observer in Things of this Nature, I, at first, imputed to my own Unskilfulness in such Enquiries, knowing my Microscope to be very good; till at last, after repeated Trials, I very plainly saw, That nothing dropt out of the Claws, which were always dry while the Spider Bit, but that a short, white Proboscis was at the same time thrust out of the Mouth, which instilled a Liquor into the Wound.
Then I concluded, That Mr Leewenhoek had Delineated the Apertures in these Weapons, only from the Analogy which he thought they must bear to the Viperine Fangs, the Sting of the Scorpion, Bee, &c. And I was confirmed in this Opinion by examining a Claw of the great American Spider, described (tho’ but lamely) by Piso [(39)], and called Nhamdu; this was given Me by Mr. Pettiver, and being above fifty Times bigger than that of the largest Europæan Spider [(40)], if there had been any Slit in it, my Glass would no doubt have discover’d it, but yet I found it to be quite Solid.