82 EVENINGS AT THE MICKOSCOPE. 



shall presently consider, so that both air and blood cir- 

 culate in them. 



In this wing of the Bee all of these structures may 

 be seen to greater advantage. The membrane appears 

 perfectly homogeneous by transmitted light, even with 

 so high a magnifying power as 600 diameters, at least on 

 a cursory examination ; though, by careful manipula- 

 tion, we may discern faint traces of angular lines which 

 divide the whole surface into irregular areas. But 

 by using reflected light at an oblique angle, this areola- 

 tion, which indicates the primary cells of the structure, 

 is much plainer, and each area is perceived to carry a 

 single hair in its centre. 



The hairs themselves here take the character of 

 curved spines, not unlike those of a rose tree. Along 

 the front edge of the wing they are straight, stout, 

 densely crowded, and overlapping in an inclined po- 

 sition ; but the most interesting modification of these 

 organs is seen at the front edge of the posterior pair. 

 Unlike the Fly, which has but a single pair of wings, 

 the Bee has two pairs, of which the fore pair is the 

 larger and more homy, the hinder pair seeming to be, 

 as it were, cut out of the hinder and inner side of the 

 fore ones. The two edges — the hinder edge of the fore 

 pair and the front edge of the hind pair — then corres- 

 pond, but it is necessary that, during flight, when the 

 wings are expanded, the two wings on each side should 

 maintain this relative position, neither overlapping the 

 other, but together presenting one broad surface, where- 

 with to beat the air. There must be, therefore, some 

 contrivance for locking together the two edges in ques- 

 tion, which yet shall be capable of being unlocked at 

 the pleasure of the animal ; for the wings during repose 

 slide over one another. This contrivance is furnished 



