278 ANNUAL OF SCIENTIFIC DISCOVERY. 



ing the form of a shallow cup. It was now placed under a microscope 

 with a power of 250 diameters, or magnifying 62,500 times. 



" Under this power the bead-like appearance, noticed with the sim- 

 ple lens, resolved itself into a definite form, resembling precisely the 

 cells of the honeycomb as they appear on the broad plane. Like these 

 cells, each division was hexagonal. The substance of each division 

 was convex exteriorly. We are reminded that this is the form which 

 economizes space the most, and that it is also the form always taken 

 by the equal sized round bodies when equally pressed together. This 

 law we see exemplified in the cellular tissue of plants, and we account 

 for the elongated form of the cells of the fibrous tissue, by unequal pres- 

 sure. We see this law in the formation of the cells of the honeycomb, 

 as equally sized globular cells equally pressed laterally, and forming 

 hexagonal cells. We see it again, though imperfectly, it is true, in 

 soap-bubbles. Might we not, therefore, infer that this peculiar form is 

 the natural effect of a known law, and that it could not assume any 

 other form ? But to remove all doubt, we must prove our premises, 

 that is, if the facets of an insect's eye, composed originally of an im- 

 mense number of spheres of equal size, equally pressed, laterally, pass 

 into the hexagonal form, or suffer any other modification. That they 

 are of equal size is manifest from simple inspection. 



" We will now see if experiments prove they are, or have been, 

 spheres ; but I must first speak of some further examination of the 

 cornea. I counted the number of facets, or faces, by the microme- 

 ter, and found in each eye 12,500, but I think they are somewhat more 

 numerous. Around each facet I found a fringe of fine hairs which 

 seem to fulfil the purpose of eyelashes. 



" I now placed the cornea in such a manner, that, in looking through 

 the microscope, and through the cornea, I could see the flame of a can- 

 dle. -I then saw, not one flame, but an immense number of flames ; in 

 fact, an illumination of candles on a large scale, which arrangement 

 quite corresponded with the hexagonal form of the facets ; thus there 

 was a row of flames, and above this another row, not one flame above 

 another, but intermediate flames in intermediate rows, and so on one 

 row with another. Each facet is then a distinct eye, producing a 

 distinct image in each facet. 



"An ordinary observer might infer that the insect saw not one ob- 

 ject, but a multitude of objects ; not one flower, but thousands, pro- 

 ducing a complete ' embarras de richessesj most confusing to the poor 

 fly. It is natural that we should be led to such a conclusion. But, on 

 the other hand, we are taught by analogy that ' Order is Nature's first 

 law.' To help us to the clue of this second point, or of this apparent 

 confusion, we will continue our experiments. Taking for granted that 

 spheres were upon the disk, I severed them with a needle and found 

 one end of the several pieces circular, and the other pointed ; in fact, 

 each separate ocellus, or eye, had the form of a cone, the basis forming 

 the facet, and the apex converging to a centre. Each was imbedded 

 in a mass of pigment, in plain terms, black paint ; with each apex 

 receiving a filament of the optic nerve. Each separate ocellus, there- 

 fore, has a separate power of vision. Each facet, cone, and filament 

 being separated from all other facets, cones, and filaments by a layer 

 of pigment, forms a separate ocellus, so circumstanced that no ray of 



