170 EVEKIN'GS AT THE MICKOSCOPE. 



a double row of glassy points, 'wliicli project from tlie 

 siirface, and are then hooked backwards. Tliese are tlie 

 mandihles, and tliey closely fold together, inclosing an- 

 other narrower blade, the npper lip, wliicli has its two 

 edges studded with similar points, bnt in a single 



JfOW. 



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

 specially armed weapons, the mandibles acting a second- 

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

 which pierce other animals with the month. But in 

 this case the mandibles are the favoured parts, the max- 

 illce, being developed into broad leaf-shaped convex 

 sheaths, inclosing the mandibles. 



There are, however, two cutting blades besides, — 

 the labial 2^(dph '^hich 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^ of which the joints are furnished at 

 their tips with tiny projecting warts, doubtless the seats 

 of a deh'cate 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 

 pot a matter of course that you will be able to repeat 

 these observations with the first specimen you put on 

 the stage of your microscope. Several favourable con- 

 ditions must combine in order to insure a successful ex- 



