Ivi INTRODUCTORY OBSERVATIONS. 



feen about the mud of rivers and putrid carcafes ; 

 whence, then, did they originate ? Some fup- 

 pofed them to come from one thing, fome from 

 another, from mud, hme, Ihells, or, as it would 

 feem, whatever the animals were nearefl to at the 

 time ; but the great fource of all was believed to 

 be putrefaftion ; that, by general concurrences 

 was admitted to be the origin of infe6ls, and 

 many other animated beings. It is inconceivable 

 how long this opinion was maintained. Ocu- 

 lar demonllration of the reverfe was hardly 

 judged conviction, and treatifes v/ere even written 

 in its fupport. Others, more watchful of the pro- 

 grefs of nature, faw an egg produced by an in- 

 fect f they kept it till a worm came forth ; and 

 preferved the worm until, by a complete meta- 

 morphofis, it changed into a winged animal'. 

 Thus was the real origin of an immenfe part of 

 the creation afcertained.^ 



It is not fo furprifmg that the fpontaneous ge- 

 neration of plants alfo gained credit in the fullefl 

 extent. The feeds were either fo minute or fo 

 difficult to be found, that they eluded the mod 

 accurate fearch, and in this manner gave foun- 

 dation to conclude that there were none. Now 

 is it univerfally received, that the origin of every 

 plant muft be from fome part of ar^ther plant ; 



and 



