328 The Microscope. 



fitting into each other, these lenses appeared to be alternately 

 concave and convex, resembling a combination of acromatic ob- 

 ject glasses in a telescope. Under the cornea I discovered a fine 

 membrane full of minute ramifications, which I presume to be 

 blood vessels, and immediately under this membrane I found a 

 corresponding number of tubes which fitted the lenses in the cor- 

 nea. I then removed the tubes, and came to the retina, in which 

 there was the same number of divisions as the above lenses, so that 

 each lens had a tube attached to it, which conveyed the image of 

 any object formed on the lens to the divisions in the retina, and 

 was from thence conveyed by numerous optic nerves to the sense 

 of seeing in the brain. 



Eggs OF Insects. The eggs of insects are remarkable for 

 figure and color, and for the regularity and exactness in which 

 they are placed. We sometimes find a sort cemented round a 

 twig of the sloe tree, damson tree, <^'C.; the variety of them is in- 

 numerable. They are found likewise in the water in spring; and 

 on water cresses and other water plants appear to the naked eye 

 only as slime. The common fly will deposit her eggs on meat 

 with the utmost regularity; which with the assistance of the mi- 

 croscope, will appear in their true form. The same maybe ob- 

 served with respect to nits on the human hair; and if fleas are 

 kept for a few days in the object box, some will be found to have 

 lain their eggs, which may be examined under the microscope. 



Wings of Insects. There is such an infinite variety in the 

 contexture and form of -the Avings of insects, and such beautiful 

 ornaments upon them, that'^none but those who have observed 

 them can have any conception of their form and color: as the 

 dragon fly, which is very transparent, dividing as it appears in 

 long squares. The wing of the female dragon fly is different, in 

 being more opaque, and forming itself into curious angles and 

 shapes. Some are covered with bristles, as all kinds of flesh 

 flies; others with feathers, as butterflies and moths. Many have 

 their wings folded under a case, as beetles, earwigs, ^'C. — most 

 of them extremely beautiful \then brought before the microscope; 

 all these wings have ribs, and blood vessels branching out at dif- 

 ferent parts of them. Under the wings of insects is a small blad- 

 der or poise; with which they balance themselves in flying; this 

 carefully taken ofl', is a very curious object. 



