11 PREFACE. 



The unaccountable theory of fpontaneous ge- 

 neration made great and rapid progrefs towards 

 the middle of laft century : it was even embrac- 

 ed by naturalifls of no inconfiderable merit. Mr 

 Needham, in fupporting a fyllem which he firm- 

 ly believed, attacked or mifcondrued fome of the 

 author's principles, who, in his turn, retorted 

 with uncommon feverity. This controverfy oc- 

 cupied a confiderable portion of the firfl; Tra^l, 

 but part of it is here omitted ; for it is certainly 

 needlefs to revive any thing concerning a doctrine 

 now totally exploded. Whoever beholds the 

 -animalcula of infufions, either with the naked 

 eye or a microfcope, in my opinion, can demand 

 no other evidence of their animation, which was 

 the principal point in difpute. All the other 

 Tracts are preferved entire as in the original. 



Several notes are fubjoined, chieay in illuflra- 

 tion of general points, and fometimes in explana- 

 tion of the text. But this is not a mode of 

 writing to be recommended ; for it diflracls the 

 attention from the fubjed, and too frequent op- 

 portunities occur of making ufelefs remarks. 

 Perhaps it will aKvays be preferable, if poffible, 

 to conned obfervations of this kind in fuch a 

 manner as to form a brief diilertation, which is a 

 much better way for a commentator to illuftrate. 

 The preliminary remarks will in a certain degree 



fupply 



