328 OPERATIVE TOOLS. 



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

 pillars, distinguished from those of butterflies and moths by 

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

 ported, they hang usually on the leaf which they are consuming, 

 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 victims 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 instrument which appeared 

 simple to our naked sight is made up in reality of three dis- 

 tinct 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. t 



This curious implement, of which it has been said justly 



* By Reaumur. t See Vignette. 



