474 



Microscopical Essays, 



A flow tremulous motion, confined to one fpot, may be per- 

 ceived at intervals ; this in a little time becomes more lively, and 

 foon pervades the whole drop. 



It's motions are, in general, very quick ; two united together 

 may fometimes be feen fwimming among the reft ; while in this 

 fituation they have been miftaken by fome writers for a different 

 fpecies, whereas it is the fame generating another by divifion. 



It is to be found in all water, though but feldom in that which; 

 is pure ; they are in great plenty in the fu miner in ditch water, 

 alio in infufions of animal or vegetable fubftanc.es, made either of 

 frefh or fait water, myriads being contained in a drop ; numbers,, 

 of various fizes,, are to be found in the filth of the teeth. 



The animal cula of this and the firft fpecies are fo numerous as. 

 to exceed all calculation, though they are contained in a very 

 confined fpace, 



6. Monas Mica. 



Monas, circulo notata. Mona, marked with a circle. 



This lucid little point may be discovered with the third lens of 

 the common fingle microfcope, when the magnifying power is 

 increafed ; it appears either of an oval or fpherical figure, for it 

 affumes either at pleafure. It is tranfparent, and has a fmall 

 ellipfe infcribed as it were within it's circumference ; this ellipfe is 

 moveable, being fometimes in the middle, fometimes a little to- 

 wards the fore -part , at others nearer the hind-part. 



r 9 There 



