112 BEES AND BEE-KEEPING. 



facets we find~Tong, and generally perfectly straight, 

 hairs, which indicate, by their basal formation, that 

 they are sensory, as well as protective, in, function. 

 The dark tone of the eye is due to the presence of 

 quantities of colouring matter (technically pigment) 

 within, and as this begins to form during the chrysa- 

 lis condition, the growing eye then passes through all 

 shades between white and an intense purplish-brown, 

 approaching black. The external lenses, which are, 

 of course, devoid of colour, and very transparent, 

 are chitinous, being developed much as the external 

 skeleton, from an underlying layer, the latter disap- 

 pearing when they are fully formed. Mutual pres- 

 sure converts outlines which would, in its absence, 

 have been, in every case, circular, into a series of 

 hexagons — in proof of which, the lenses on the margin 

 of the eye (G) are bounded by a curve wherever 

 they are free; while those of the chrysalis are 

 circular, until they grow sufficiently large to bri no- 

 pressure upon each other. 



If a specimen be properly prepared by hardening, 

 and then cut in cross section, the contiguous sets of 

 parts (ommatidia) are found almost in the form of a 

 fan (C). The superficial lenses, making up together the 

 cornea, are now seen to be bi-convex, while, beneath 

 each, is placed a second lens (the crystalline cone, 

 cc, C and D). (For the examination of the cornea and 

 crystalline cones, the directions at page 76 are suffi- 

 cient ; but, for the finer parts, teasing with needles, 

 after soaking the optic tract for twenty-four hours 

 in a 5 per cent, solution of chloral hydrate, is neces- 

 sary, unless staining and section-cutting, after har- 



