These being their eyes, it affords us a very pretty Speculation to contemplate their manner of vision, which, as it is very differing from that of biocular Animals, so is it not less admirable.

That each of these Pearls or Hemispheres is a perfect eye, I think we need not doubt, if we consider onely the outside or figure of any one of them, for they being each of them cover’d with a transparent protuberant Cornea, and containing a liquor within them, resembling the watry or glassie humours of the eye, must necessarily refract all the parallel Rays that fall on them out of the air, into a point not farr distant within them, where (in all probability) the Retina of the eye is placed, and that opacous, dark, and mucous inward coat that (I formerly shew’d) I found to subtend the concave part of the cluster is very likely to be that tunicle or coat, it appearing through the Microscope to be plac’d a little more than a Diameter of those Pearls below or within the tunica cornea.  And if so, then is there in all probability, a little Picture or Image of the objects without, painted or made at the bottom of the Retina against every one of those Pearls, so that there are as many impressions on the Retina or opacous skin, as there are Pearls or Hemispheres on the cluster.  But because it is impossible for any protuberant surface whatsoever, whether sphaerial or other, so to refract the Rays that come from farr remote lateral points of any Object as to collect them again, and unite them each in a distinct point, and that onely those Rays which come from some point that lies in the Axis of the Figure produc’d, are so accurately refracted to one and the same point again, and that the lateral Rays, the further they are remov’d, the more imperfect is their refracted confluence; It follows therefore, that onely the Picture of those parts of the external objects that lie in, or neer, the Axis of each Hemisphere, are discernably painted or made on the Retina of each Hemisphere, and that therefore each of them can distinctly sensate or see onely those parts which are very neer perpendicularly oppos’d to it, or lie in or neer its optick Axis.  Now, though there may be by each of these eye-pearls, a representation to the Animal of a whole Hemisphere in the same manner as in a man’s eye there is a picture or sensation in the Retina of all the objects lying almost in an Hemisphere; yet, as in a man’s eye also, there are but some very few points which liyng in, or neer, the optick Axis are distinctly discern’d:  So there may be multitudes of Pictures made of an Object in the several Pearls, and yet but one, or some very few that are distinct; The representation of any object that is made in any other Pearl, but that which is directly, or very neer directly, oppos’d, being altogether confus’d and unable to produce a distinct vision.