DIFFERENTSY STEMS. 75 



ingly improper : Though it be true, that ani- 

 mals havmg blood are diftinguifhed into male 

 and female, it is by no means equally true, that 

 bloodlefs animals are, for the moft part, herma- 

 phrodites : For the only hermaphrodites we 

 know, are land-fnails and worms ; but we are 

 uncertain whether all fhell-animals, and all thofe 

 which have no blood, be alfo hermaphrodites. 

 This muft be learned from the particular hiftories 

 of thefe animals. And, with regard to thofe 

 which are alledged to proceed from putrefaction, 

 as Ariftotle gives no enumeration of them, 

 many objedions occur ; for moft fpecies which 

 the ancients believed to proceed from putre- 

 fadion, have, by the moderns, been difcovered 

 to proceed from eggs. 



Ariftotle makes a fecond divifion of animals, 

 namely, into thofe which have the faculty of pro- 

 greftive motion, and thofe which have no fuch fa- 

 culty. All animals who move, and have blood, 

 are diftinguillied by fexes : But thofe which, 

 like oyftcrs, adhere to one place, or hardly move 

 at all, have no fexes, and, in this refpcdt, re- 

 fcmble plants ; and it is only, he obferves, from 

 difference in bulk that they have been diftin- 

 guifhed into male and female. It muft be ac- 

 knowledged, that we are ftill uncertain whether 

 fiiell-animals have fexes : Among oyfters, fome 

 individuals are fertile, and others not. The fer- 

 tile individuals are diftinguifhed by a delicate 

 edging or border which furround their bodies, 



and 



