ourthly, that the rest of the capacity of the clusters was in some, as in
Dragon Flies, &c. hollow, or empty; in others fill'd with some kind of
substance; in blue Flies, with a reddish musculous substance, with _fibres_
tending from the center or bottom outwards; and divers other, with various
and differing kinds of substances.

That this curious contrivance is the organ of sight to all those various
_Crustaceous_ Animals, which are furnish'd with it, I think we need not
doubt, if we consider but the several congruities it has with the eyes of
greater creatures.

As first, that it is furnish'd with a _Cornea_, with a _transparent
humour_, and with a _uvea_ or _retina_, that the Figure of each of the
small _Hemispheres_ are very _Spherical_, exactly polish'd, and most vivid,
lively and plump, when the Animal is living, as in greater Animals, and in
like manner dull, flaccid, and irregular, or shrunk, when the Animal is
dead.

Next, that those creatures that are furnish'd with it, have no other organs
that have any resemblance to the known eyes of other creatures.

Thirdly, that those which they call the eyes of Crabs, Lobsters, Shrimps,
and the like, and are really so, are _Hemispher'd_, almost in the same
manner as these of Flies are. And that they really are so, I have very
often try'd, by cutting off these little movable knobs, and putting the
creature again into the water, that it would swim to and fro, and move up
and down as well as before, but would often hit it self against the rocks
or stones; and though I put my hand just before its head, it would not at
all start or fly back till I touch'd it, whereas whil'st those were
remaining, it would start back, and avoid my hand or a stick at a good
distance before it touch'd it. And if in _crustaceous_ Sea-animals, then it
seems very probable also, that these knobs are the eyes in _crustaceous_
Insects, which are also of the same kind, onely in a higher and more active
Element; this the conformity or congruity of many other parts common to
either of them, will strongly argue, their _crustaceous_ armour, their
number of leggs, which are six, beside the two great claws, which answer to
the wings in Insects; and in all kind of Spiders, as also in many other
Insects that want wings, we shall find the compleat number of them, and not
onely the number, but the very shape, figure, joints, and claws of Lobsters
and Crabs, as is evident in Scorpions and Spiders, as is visibl