INTRODUCTORY OBSERVATIONS. Xxili 



.come vifible in water. Though imperceptible 

 by our fenfes, they may be fufpended in the ah* 

 ;as their native element ; and, if it was not for 

 the exceflive delicacy of their parts, and the 

 difficulty of obfervation, they might be rendered 

 vifible by the interpofition of different mediums ; 

 — and here imagination may figure beings of an- 

 other kind, which, by an interpofing medium, 

 may in the fame manner be brought mto viev/. 

 -Some animalcula of confiderable fize are feen 

 with the utmoft difficulty, from extreme tranf- 

 parency ; it is only an accidental infledion, or 

 an alteration of the ufual direction of the rays of 

 light, that renders them vifible. 



11. Seminal Vermiculi.' — Three great and 

 important points are to be confidered in animat- 

 ed exiftence ; the mode of an animal's origin and 

 introduftion into the world ; the duration of hfe ; 

 and the manner of it's death. What we daily 

 behold, events and objefls continually familiar to 

 us, make little impreffion ; and, if there is any no» 

 velty at firft, it foon wears away. If we refleft 

 on the phenomena of nature, and inquire into the 

 original caufe of life, its prefervation and end, 

 an infinite and unaccountable variety is prefent- 

 cd ; and although v;e may be inclined to give 

 phyfical reafons in explication, or feel an internal 

 convidion that none other will apply to certain 

 c 4 cafc^^j 



