( 138 ; 



On my return home, I examined thefe gall-nuts more accurately, 

 and found tliat each of them had a cavity in the middle, wherein 

 lay a living white worm, which had very little motion : it was 

 thick, in proportion to its length, and lay bent m a circular form, 

 the body of it confifting of thirteen or fourteen rings, as we fee 

 fdk-worms and caterpillars, and thefe covered with pointed hairs. 



It feemed to me worthy of obfervation, that, from this 

 time, I obferved thefe worms, or maggots, continue alive to the 

 end of December ; and that, in gall-nuts which I had gathered in 

 the fummer, and which were fo dried, that I thought they were 

 Ihrunk to half their former fize ; whereupon I concluded that the 

 worms, for want of fufficient nourifliment, had not arrived at their 

 full growth, fo as to be changed into flies, and had only been 

 fupplied with food fufficient to keep them alive. But, wiien they 

 had grown to be fomewhat larger than a great pin's head, then 

 I faw the eyes beginning to be formed, wliich were of a black colour. 



After this, I went occafionally into the wood at the Hague, in 

 order to purfue my fpcculations, and obferved that thelc worms 

 were changing into flies ; for, I not only could fee their eyes per- 

 fe6lly formed, but I alfo could difcern plainly their horns and 

 feet, and the hind part of their bodies. Tliis infeft then lay with- 

 out any motion tliat I could perceive, with its feet, fix in number, 

 and its two horns lying in regular order clofe to its body, in like 

 manner as we fee in the aurelia of the filk worm, before it comes 

 out of its fliell, or covering, but in this animalcule I did not 

 then obfcrve any fuch cafe or covering ; but only the fliape of a 

 fmall fly without wings, the hind part of its body of a round form 

 and of a fliining black colour, and which in a fliort time was 

 provided with two larger and two fmaller wings ; and I after- 

 wards found that thefe aurelias had a thin covering, \\ hich enclofed 

 the body, but not the feet. 



From thefe my obfervations, I concluded, that tlicfe animalcules 



