EVENINGS AT THE MICROSCOPE 



little friends in some particulars. For example, the two 

 inner lancets seem to be united in one, in Reaumur's spe- 

 cies, or else, which I think more probable, he did not 

 succeed in separating them. 



He describes the two curved spoon-shaped pieces as 

 finely indented on both sides with teeth; which are strong, 

 nine in number, arranged with great symmetry, increasing 

 in fineness toward the point. This instrument he describes 

 as composed of three pieces, the two exterior, which he 

 calls the files, and another pointed, which he compares 

 to a lancet, which is not toothed. "The files are capable 

 of being moved forward and backward, while the centre 

 one remains stationary; and as this motion is effected by 

 pressing a pin or the blade of a knife over the muscles on 

 either side at the origin of the ovipositor, it may be pre- 

 sumed that those muscles are destined for producing sim- 

 ilar movements when the insect requires them. By means 

 of a finely-pointed pin carefully introduced between the 

 pieces, and pushed very gently downward, they may be, 

 with no great difficulty, separated in their whole extent. 



"The contrivances by which those three pieces are held 

 united, while at the same time the two files can be easily 

 put in motion, are similar to some of our own mechanical 

 inventions, with this difference, that no human workman 

 could construct an instrument of this description so small, 

 fine, exquisitely polished, and fitting so exactly. We 

 should have been apt to form the grooves in the central 

 piece, whereas they are scooped out in the handles of the 

 files, and play upon two projecting ridges in the central 

 piece, by which means this is rendered stronger, M. 

 B^aumur discovered that the best manner of showing the 

 play of this extraordinary instrument is to cut it off with 



