The anatomy of humane bodies epitomized wherein all parts of man's body, with their actions and uses, are succinctly described, according to the newest doctrine of the most accurate and learned modern anatomists / by a Fellow of the College of Physicians, London.

CHAP. XXI.

Of the Humours and Vessels of the Eye.

NEXT to the Tunicles of the Eyes are the Humours contained in them to be conside∣red.* 1.1 And these are in number three, viz. Aqueus,

Crystallinus, and Vitreus. The second weighs as much again as the first, and yet not so much as the third by a sixth part. The Crystalline is the most d••nse of consistence by much; and the glassy more dense than the watry.

The Aqueous humour is outermost,* 1.2 being pel∣lucid and of no colour (as neither are the other two.) It fills up that space that is betwixt the Cornea and the Crystalline humour before. If any thickish particles swim in it, then Gnats, Flies, Spiders webs and the like will seem to be ••lying before the Eyes. But if those particles grow still thicker, and close together so as to make a film, and this be spread before the hole of the Pupilla, then is the sight quite taken away, which disease is called a Cataract.

The Crystalline humour (so called from its be∣ing as clearly transparent as Crystal) is placed betwixt the aqueous and the vitreous,* 1.3 but not exactly in the middle or centre of the Eye, but rather towards its fore-part. It is inclosed in the bosom as it were of the vitreous humour, and is flattish on the foreside, but rounder behind. It is more bright and solid than either of the other two. It has been the common opinion that it is inclosed in its proper Membrane, which is called either Crystallina from its transparency, or Aranea from its most fine contexture. But Dr. Briggs, a very accurate Anatomizer of the Eye, denies any such Tunicle, affirming that it is meerly ad∣ventitious when the humour is exposed for some while to the Air, or is gently boiled. As to the collection or reception of the rayes of things vi∣sible, this humour is the primary instrument of sight: though as was said before, the Tunica retina

is the principal as to perception, because through it the rayes are communicated to the common sensory.

The third and last humour of the Eye is the Vitreous,* 1.4 so called because it is like to molten glass. This is thicker than the Aqueous, but thinner than the Crystalline; and much exceeds them both in quantity, for it fills up all the in∣ner or hinder he••isphere of the globe of the Eye, and a pretty deal (toward the superficies) of the formore. It is round behind, but hollowed in the middle forwards, to receive the Crystalline into its bosom. This humour is also said to be separated from the other two by a proper Tuni∣cle, called Vitrea, which the aforesaid ingeni∣ous Author likewise denies.

See the situation of these Humours represented in Fig. 2. of the Table inserted p. 341.

The Eyes have Arteries from the Carotides,* 1.5 which bestow twigs on their Muscles, and on their Tunicles. And these are accompanied with Veins springing from the branches of the Jugulars. As for their Nerves, they either assist the sense of seeing, and are called the optick Nerves, which we have reckoned for the second pair and descri∣bed before Chap. 10. or serve for the moving of them, being inserted into their Muscles, and to this purpose serve the third and fourth pair, and some twigs of the fifth. As to their Lympheducts, we have spoken of them above Chap. 19. when we discoursed of the Glands placed at each canthus or corner of the Eye-lids.

Notes

• * 1.1

  The ••••∣mours of the Eye three.
• * 1.2

  1. Aqueus.
• * 1.3

  2. Crystal∣linus.
• * 1.4

  3. Vitreus.
• * 1.5

  The vessels of the Eye.