124 MONADS. 



the monad, the simplest of animalcules, are already 

 known. The only locomotive organ hitherto dis- 

 covered is a proboscis issuing from near the mouth ; 

 the vibratory or rotatory motions of which give it 

 the appearance of numerous cilia. 



The characteristic of another species is a minute 

 red eye-like speck, situated within the creature, at 

 the anterior part of the body, which is considered to 

 be a rudimentary visual organ. And a minute and 

 careful inspection of these living atoms, proves that 

 they have a sensitive organization as conformable to 

 their particular uses, and as well adapted to the 

 wants and comforts of these microscopic beings, as 

 the largest fish. One family of these creatures is 

 provided with a distinct, gelatinous, membranous, 



or shell-like substance, termed a lorica, in which 

 they are more or less inclosed. This covering 

 appears in different forms ; sometimes as an open 



