170 



EVENINGS AT THE MICEOSCOPE. 



a double row of glassy points, -wliicli project from the 

 surface, and are then hooked backwards. These are the 

 mandibles, and they closely fold together, inclosing an- 

 other narrower blade, the tipper lip, which has its two 

 edges studded with similar points, but in a single 

 row. 



In general, as we have seen, the maxillm are the 

 specially ai-med weapons, the mandiMes acting a second- 

 ary part, often serving as mere sheaths — in those insects 

 which pierce other animals with the mouth. But in 

 this case the mandibles are the favoured parts, the m,ax- 

 illce being developed into broad leaf-shaped convex 

 sheaths, inclosing the onandibles. 



There are, however, two cutting blades besides, — 

 the labial palpi, which have their upper edge thick, 

 divided into four distinct joints, and set with bristles, — 

 thus retaining the proper palpine character, while their 

 . under edge is thinned away to a fine keen blade, in 

 which there is no sign of jointing. Then there are the 

 maxillary palpi, oi which the joints are furnished at 

 their tips with tiny projecting warts, doubtless the seats 

 of a delicate perception, and hollowed into a double 

 series of chambers, which are filled with a dark-coloured 

 fluid. 



All this is very interesting to behold, and is calcu- 

 lated to exalt our ideas of the wonderful and inexhaust- 

 ible resources of Omnipotence, as well as to humble us, 

 when we reflect on how little we certainly understand 

 even of what we see. But common as the Flea is, it is 

 not a matter of course that yovi will be able to repeat 

 these observations with the first specimen you put on 

 the stage of yoiir microscope. Several favourable con- 

 ditions must combine in order to insure a successful ex- 



