12 The BOOK of 
{cope, for then only one part of the convexities 
can be feen, and the other not at all; and 
thus falfe angles are exhibited. Almoft all 
concave bodies, if viewed in the light, appear 
to our fight fometimes globular, and fome- 
times roundith and convex: this is illuftrated 
very particularly by the engraved agats. For 
this reafon the greateft circumfpection muft 
be always ufed in viewing objects by micro- 
fcopes, left we fhould deceive ourfelves, 
which has commonly happened on thefe occa- 
Gons. I fhall hereafter explain what produces 
thefe hexangular divifions in this net of the 
eye. The thicknefs of the cornea in the Bee 
is pretty confiderable, and indeed more fo, 
confidering its fize, than in many other infects 
which are equally fmall: this may in fome 
meafure be comprehended from a {mall piece 
of it delineated as it appears under the micro- 
{cope at the letters ///, Tab. XX. fig. i. 
Between the divifions we have been hitherto 
defcribing, are placed thofe hairs which I have 
before faid are planted all over the eye. They 
are very firmly fixed to the cornea, for they 
pierce it all through in the fame manner as 
our hair does skin: but they rife fharp-pointed, 
and are three or four times longer than the 
diameter of any one hexagonal divifion: in 
ftructure they refemble briftles, and are of a 
round figure, thick below and fharp above. 
‘Their number is likewife very confiderable, 
though lefs than the number of the divifions ; 
they are, however, fo thick and fo clofe fet 
together, that they feem to conftitute a very 
clofe foreft of briftles, like fo many fir-trees 
planted upon the eye: this may be feen in 
fome meafure under the letters eee, fig. 1. 
where I have reprefented them only in the 
circumference of the divifions of the eye: of 
the other divifions that are exhibited in the 
fame figure, I have delineated a lefs and 
determinate number, they being very nu- 
merous, and hitherto beyond any account I 
have taken. Finally, I fhould think thefe 
hairs are principally fixed here to guard the 
eye againft any thing falling on, or ftriking 
againft it; to keep off the duft, and, in cafe 
any of thefe annoyances fhould -flip in, to 
aflift the Bees to throw, or brufh it out the 
more eafily, by a friction, which the Bees 
perform with their feathered legs: Flies alfo 
ufe the fame method to wipe themfelves. 
Thefe hairs feem alfo to ferve the Bees inftead 
of eye-brows or eye-lafhes. Thad firft thought 
that only the long-lived {pecies of infects, fuch 
as Bees, had thefe hairs: but I afterwards 
obferved that they are not fo peculiar to the 
Bees, as not to be found in many other {pecies 
of infe@ts. I have found them among others 
in the coloured diurnal Butterfly: I have like- 
wife found them on the eye of Goedaert his 
Bee. This eye, however, is not covered all 
round with thefe hairs, but only fhews the 
oval orbit planted with them. Goedaert 
defcribes the Bee I have juft mentioned, in 
the fecond experiment in his firft part; but 
Ni AST? UR BS or, 
if any one examines this more accurately, he 
will find it is only a dunghill Fly, with no 
more than two wings, and conftantly pro= 
duced or generated annually in the fame 
manner. It is produced from a Worm with 
a long tail and very fhort legs, found in dung- 
hills and common-fhores, and belongs to the 
fourth order of our natural tranfmutations. 
The Bee, on the contrary, is to be ranked in 
the third order, as I have already fufficiently 
proved. I fhall proceed to defcribe the uvea, 
which is the other coat of the Bee’s eye. Of 
the other three remarkable little eyes I hall 
treat at large hereafter. . 
When the cornea is removed from the in- 
ternal parts of the eye, the tunica or coat, 
underftood to be the uvea, comes in view. 
This, therefore, is not placed in infects at the 
bottom of the eye, but next to the furface ; 
nor does it any where appear perforated as in 
large animals. This confequently prevents 
the rays of light penetrating further into the 
eye than through the cornea only. When 
the cornea is taken from the eye, we ufually 
fee that a more opaque matter, which entirely 
takes away the peripicuity or clearnefs of the 
cornea, is carried off with it. This matter is of 
different colours in different animals ; in Bees 
it is of a deep purple, in other infects it is 
green, in fome blue, in others black, and in 
others again it has a very beautiful mixture 
of various colours, which are elegantly and 
agreeably feen through the cornea. But this 
is to be found only in the inner furface of the 
cornea, where the uvea adheres next that 
coat, without any thing between. The two 
parts of this matter which conftitutes the 
uvea, both that which is applied to the inner 
cavity of the cornea, and that alfo which is 
obferved to adhere to the internal parts of the 
eye, are commonly of a blackifh colour, and 
the laft likewife {tains the fingers when touch- 
ed, and is a kind of black paint, as our uvea 
and that of other animals is: and hence it 
arifes, as I have before obferved, that the 
perfpicuity of the cornea is darkened or ob- 
{cured by this matter. Therefore, in order to 
fhew the cornea pellucid, this matter muft be 
firft wiped off with the help of a pencil or a 
{mall piece of paper folded up. If you prefs 
the head of the Fly between two folds of 
paper, the paper acquires a purple colour from 
it, which is owing to the more diffufed co- 
lour of the uvea. But perhaps fome one will 
ask, if the matter hitherto defcribed feems 
only to be the uvea, but is not fo in reality, 
what is it? To this I anfwer, that this matter 
is nothing but the tops of fome broken fibres, 
which are placed clofe under the cornea, Tab. 
XX. fig. 1. gg: for no humours, properly fo 
called, are found in any part of the Bee’s eye, 
which isa thing well worth obferving : though 
the celebrated Dr. Hooke, for want of a fuffi- 
cient number of experiments, hath been led 
to imagine there were fuch in the eye of the 
Libella; becaufe no other method occurred 
to 
