298 THE PHILOSOPHY 



of which every man may eafily fatisfy himfelf. Examine the com- 

 mon oak-galls, or thofe of any other tree ; if any of them happen to 

 have no aperture, cut them gently open, and you are certain to find 

 an egg, a worm, a chryfalis, or a fly: But in fuch as are perforated 

 by a cylindrical hole, not a veflige of an animal is difcoverable. The 

 galls which make an ingredient in the compofition of ink are thick, 

 and their texture is very ftrong and compad : That the fmall ani- 

 mals they contain fhould be able to pierce through fuch a rigid fub- 

 ftance is truly wonderful- ^ 



In the general order of Nature among oviparous animals, each 

 egg includes one embryo only. A Angular fpecies of eggs, however, 

 difcovered by the celebrated Mr Folks, late Prefident of the Royal 

 Society of London, muft be excepted. He found great numbers of 

 them in the mud of fmall rivulets. In fize they equalled the head 

 of an ordinary pin. They were of a brown colour, and their fur- 

 face was cruftaceous, through which, by employing the microfcope, 

 feveral living worms were diftindlly perceptible. &y dexteroufly 

 breaking the fhell, he diflodged them ; and he found with furprife, 

 that eight or nine worms were contained in, and proceeded from, 

 the fame egg. They were all well formed, and moved about with 

 great agility. Each of them was inclofed in an individual membra- 

 nous covering, which was extremely thin and tranfparent. It were 

 to be vvifhed that the transformations of thefe extraordinary animals 

 had been traced. 



Some caterpillars, when about to transform, make a belt pafs 

 round their bodies. This belt is compofed of an aflemblage of fiik- 

 en threads fpun by themfelves, the ends of which they pafte to the 

 twigs of buflies, or other places where they choofe to attach their 

 bodies. They likewife fix their hind legs in a tuft of filk. After 

 transformation, the chryfalids remain fixed in the fame manner as 



before 



