Page:Philosophical Transactions - Volume 013.djvu/181

 tended surely by Nature for some extraordinary end. Thus that of the optic Nerves in order to their consent requir'd a corresponding tension in their Fibres, or else Vision had been always double, since those Nerves arise separately from two distinct eminences of the brain: but the other Nerves arising closer together (whereby there may be a communication between their Fibres) or belonging to senses that require not so minute discrimination of objects as Vision does, there needed not that exactness in the placing or tension of the Fibres.

5. In the position of the Fibres of the Optic Nerves I fhew that they keep their distinct order, and consequently that they are not mixt or blended together at the place of their connexion (as was frivolously suppos'd by Authors before to solve the Union of Vision). And this I observ'd not only from what is noted in Man by Vesalius, Riolan, and others in their particular remarks in this Case, but also by what Nature it self shews in the Chamæleon and several of the feebler sort of Fishes, where they are scarce join'd; and this she might intend in these small or helpless creatures (who turn thereby their Eyes to several objects and different coasts at once.) to avoid those on all sides that infest them, or to catch the more readily their fleeting food; whereas others that have 'em closer join'd view particular objects the better by looking more steadily or intently toward one part, and are otherwise provided for in their food or their safety.

6. I observ'd that in the insertion of these Fibres into the Eye (where the Medullary part of them forms the Retina) they still kept their distinct series, and that they are much kept in, not only by being fastne'd (or terminating) on the processus ciliares, but also by little transverse Fibres (that are not described in the Figure I have given) which serve to connect those that run long-waies, there described's and make the whole Coat appear in a glass cf clear water like Lawn or Tiffany as I have shewn. None that I know ever