500 THE MICROSCOPE. 



which at first appear to consist of a single piece; but 

 upon closer inspection four plates are seen to enter into 



Fig. 255. The Caterpillar and Saw-fly of Gooseberry-Tree. 



their construction : namely, two saws, placed side by side, 

 as in fig. 206 ; and two supports, somewhat like the saws 

 in shape. A deep groove runs along the thicker edge 



Fig. 256. Saws of Saw-fly. (The small circle encloses the same nearly the 

 natural size.) 



of the latter, which is so arranged that the saws glide 

 backwards and forwards, without a possibility of running 

 out of the groove. When the cut is made, the four are 

 drawn together; and through a central canal, which is 

 now formed by combining the whole, an egg is protruded 



