Microscopical Essays. 



627 



dife over, by means of the microfcope, a great number of minute 

 reddifh globules, which are the animalcula themfelves. It is moft 

 proper to obferve them firft with the third or fourth magnifiers, 

 and then to ufe thofe which are deeper. 



This little creature has fome likenefs to a caterpillar; it's mo- 

 tion from place to place is performed like many of thofe infects, 

 by firft fixing the tail to fome fub fiance, then extending the whole 

 body, and fixing the head, then drawing the tail to it ; by thefe 

 alternate actions it moves with fome degree of fwiftnefs. 



It very often changes it's appearance, and affumes a different 

 form ; for the fnout being drawn inwards, the fore-part becomes 

 clubbed, and immediately dividing, exhibits to our view two cir- 

 cular inftruments, fet with minute hairs, that move very brifldy, 

 fometimes in a rotatory manner, fometimes in a kind of trembling, 

 or vibratory mode. An aperture, or mouth, is alfo perceived 

 between the two femicircles ; the animal may often be feen fwim- 

 ming about in purfuit of food while in this ftate. 



The moft diftinguifhing parts of this animalculum are the head, 

 the thorax, and the abdomen. The form and ftru&ure of the 

 head is wonderful, differing from any other creature hitherto 

 defcribed • the fudden change of the head from one form to ano- 

 ther is equally furprizing and fmgular ; for from being of a very 

 taper form, it becomes on a fudden as broad as any part of the 

 infecl, and protrudes an amazing piece of machinery, formed to 

 procure it's food. 



4 G 2 



The 



