68 



arranged, all the rest is easy, inasmuch as these are a 

 firm support to all that follow them. 



These are circumstances sufficiently extraordinary in 

 this little animal : but it offers something still more 

 curious in the method of its propagation. However 

 similar insects of the gnat kind are in their appearances, 

 yet they differ widely in the manner in which they are 

 brought forth ; for some are oviparous, some vivipa- 

 rous, some are males, some are females, some are of 

 neither sex, yet still produce young, without any co- 

 pulation whatsoever. This is one of the strangest dis- 

 coveries in all natural history ! A gnat separated from 

 the rest of its kind, and enclosed in a glass vessel, with 

 ajr sufficient to keep it alive, shall produce young, 

 which also, when separated from each other, shall be 

 the parents of a numerous progeny. Thus down for 

 five or six generations do these extraordinary animals 

 propagate in the manner of vegetables, the young burst- 

 ing from the body of their parents, without any pre- 

 vious impregnation. At the sixth generation, how. 

 ever, their propagation stops ; the gnat no longer 

 produces its like from itself, but requires the access of 

 the male. 



14. A Cicadula 5s a small insect found in May and 

 June, on the stalks or leaves of plants, in a kind of 

 froth commonly called Cuckoo.spit. This froth is not 

 from the plant, but the mouth of the animal ; and if it 

 be gently wiped away, will be presently seen issuing 

 out of its mouth, till there is as large a quantity of it as 

 before. They are of tho shape of a louse, some being 

 whitish, some yellowish; and others green. They often 

 change their skins while they live in this froth, and 

 only creep a little. But when they leave the plant 

 they hop and tiy, having wings which cover the whole 

 body. 



The Cochineal is an insect of the same species with 

 the gall insect. It is found adhering to several plants, 

 but only one communicates its valuable qualities to it, 



