174 EVENINGS AT THE MICROSCOPE 



jecting warts, doubtless the seats of a delicate perception, 

 and hollowed into a double series of chambers, which are 

 filled with a dark-colored fluid. 



All this is very interesting to behold, and is calculated 

 to exalt our ideas of the wonderful and inexhaustible re- 

 sources 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 you will be able to repeat these observations 

 with the first specimen you put on the stage of your mi- 

 croscope. Several favorable conditions must combine in 

 order to insure a successful examination. You should 

 choose a female Flea, partly because of her greater size, 

 and partly because the predatory weapons are better devel- 

 oped, in all these piercing and sucking insects, in the fe- 

 males true Amazons. Then you will find it needful to 

 amputate the head, in order to get rid of the front legs, 

 the thick thighs of which else impede your sight of the 

 mouth, being projected on each side of it. And this is 

 a delicate operation: it must be performed on a plate of 

 glass, under a lens, with one of those dissecting needles 

 whose points are ground to a cutting- edge. Next, having 

 severed the head, you must place it in a drop of water, 

 between the plates of your compressorium, the graduated 

 pressure of which, by means of the screw, will cause 

 the organs of the mouth to open and expand separately. 

 Finally, you must have a good instrument, and a high 

 power: less than 600 diameters will not avail to bring out 

 distinctly the toothing of the mandibles and labrum; and 

 even then you will need delicate manipulation and a prac- 

 ticed eye. But the object is worthy of the care bestowed 

 upon it. 



