152 FUNCTIONS AND INSTINCTS. 



These minim animals may be said almost to 

 be universally dispersed ; they inhabit the sea, 

 the rivers, and other waters ; are supposed to float 

 in the air ; they are found in the blood and urine ; 

 in the tartar of the teeth ; in animal substances ; 

 in vinegar ; in paste ; in vegetable substances ; 

 in fruits, seeds, and grain ; in sand ; amongst 

 tiles ; in wells ; on mountains, &c. Their num- 

 bers are infinite ; hundreds of thousands may 

 be seen in a single drop of water ; their minute- 

 ness is extreme, some being not more than ^oW 

 part of a line in length, and yet these atoms of 

 animals have a mouth and several stomachs. 



Let a man, says Dalyell, the translator of 

 Spallanzani, conceive himself in a moment 

 conveyed to a region where the properties, and 

 the figure and motions of every animal are 

 unknown. The amazing varieties of these 

 will first attract his attention. One is a long 

 slender line ; another an eel or serpent ; some 

 are circular, elliptical, or triangular ; one is a 

 thin flat plate ; another like a number of reticu- 

 lated seeds ; several have a long tail, almost 

 invisible; or their posterior part is terminated 

 by two robust horns ; one is like a funnel ; 

 another like a bell, or cannot be referred to 

 any object familiar to our senses. Certain 

 animalcules can change their figure at plea- 

 sure: 1 sometimes they are extended to immo- 



1 PLATE I. FIG. 3. 



