Note l. 8. c. 3. Note (a) — BOOK VIII.

[a] The Cornea of Flies, Wasps, &c. are so common an Entertainment with the Microscope, that every body knows it is a curious Piece of Lattice-work. In which this is remarkable, that every Foramen is of a lenticular Nature; so that we see Objects through them topsey-turvey, as through so many convex Glasses: Yea, they become a small Telescope, when there is a due focal Distance between them and the Lens of the Microscope.

This lenticular Power of the Cornea, supplies, (as I imagine,) the Place of the Crystalline, if not of the vitreous Humour too, there being neither of those Humours that I could ever find, (although for Truth Sake, I confess I have not been so diligent as I might in this Enquiry;) but instead of Humours and Tunicks, I imagine that every Lens of the Cornea, hath a distinct Branch of the optick Nerve ministring to it, and rendring it as so many distinct Eyes. So that as most Animals are binocular, Spiders for the most Part octonocular, and some, (as Mr. Willughby thought, Raii Hist. Insect. p. 12.) senocular; so Flies, &c. are multocular, having as many Eyes as there are Perforations in their Cornea. By which Means, as other Creatures are oblig’d to turn their Eyes to Objects, these have some or other of their Eyes ready plac’d towards Objects, nearly all round them: Thus particularly it is in the Dragon-Fly, (Libella,) the greatest Part of whose Head is possess’d by its Eyes: Which is of excellent Use to that predatious Insect, for the ready seeing and darting at small Flies all round it, on which it preys.