328 OPERATIVE TOOLS. 



all the species, which are many, are, in their first stage as 

 caterpillars, distinguished from those of butterflies and moths 

 by their many feet from sixteen to twenty-eight. By these 

 supported, they hang usually on the leaf which they are con- 

 suming, with the hinder part of their bodies rolled up in a 

 spiral coil. The gooseberry, the currant, the rose, the willow, 

 the turnip, and the wheat-plant, are foremost among the vic- 

 tims of their extensive depredations. 



Here is another tool of surpassing nicety, lodged in a closely- 

 fitting sheath, from which, on slight pressure, it is seen pro- 

 truding. It is large enough for partial examination even by 

 the naked eye, and, when thus viewed, appears a spike of 

 equal thickness, except at the point, where it is broader and 

 angular, and on both sides indented with teeth. Now let us 

 behold it in the microscope. The teeth, strong and sharp, are, 

 we can see now, about twelve in number, on either side, 

 and diminish in size as they approach the point. But what 

 else reveals our magnifier ? Why, it shows that the instru- 

 ment which appeared simple to our naked sight is made up 

 in reality of three distinct pieces (separable in their length), 

 the two outer ones armed, as before described, with teeth, and 

 called* " files," the central one pointed like a lancet, and not 

 denticulate. The side pieces can be moved backwards and 

 forwards, while the middle one remains stationary.f 



This curious implement, of which it has been said justly 



* By Keaumur. t See Vignette. 



