KILLING OF INSECTS. 391 



to be neither painful nor injurious, yet decisive, and 

 communicative with pleasure ; I mean the prussic 

 acid. This fluid may be imbibed by the insect 

 without producing any particular effect; but, if 

 brought to act upon the spinal cord, or what at 

 least is analogous to that part of a vertebrate animal, 

 whatever it may be called, and which seems to be 

 the most vital part of the creation, instant death en- 

 sues. A crow quill must be shaped into a point, like 

 a rather long pen, this point dipped into the prussic 

 acid, and an incision made with it immediately be- 

 neath the head into the middle of the shoulders of the 

 creature, so as to permit the fluid it contains to enter 

 into the body of the insect. Immediately after this, 

 in every instance in which I have tried it, a priva- 

 tion of sensation appears to take place, the corporeal 

 action of the creature ceasing, a feeble tremulous 

 motion of the antennae being alone perceptible ; 

 and these parts seem to be the last fortress that 

 is abandoned by sensation, as they are the primary 

 principle of sensibility when life is perfect: ex- 

 tinction of animation ensues, not a mere suspension, 

 but an annihilation of every power, muscular and 

 vital. As one example of the decisive effects of 

 this fluid, I shall instance the common wasp, a 

 creature so remarkably tenacious of sensation, or 

 so long retaining a muscular power, that it may 

 remain, as every one knows, for days crushed in 

 the window, an apparently dead insect, yet upon 



