Microscopical Essays. 



457 



Animaleulum fignifies a little animal, and therefore the term 

 might be applied to every animal which is confiderably inferior in 

 fize to ourfelves. It has been cuftomary, however, to diftinguifh 

 by this name only thofe animals that are of a fize fo diminutive 

 that their true figure cannot be difcerned without the affi fiance of 

 glades, and is more efpecially applied to fuch as are altogether 

 invifible to the naked eye, and cannot be perceived even to exili 

 but by the aid of mierofcopes. 



By thefe we are brought into a new world, and numberlefs ani- 

 mals are difcovered, which, from their minutenefs, muft other- 

 wife for ever have efcaped our obfervation : and how many kinds 

 of thefe invifibles there may be, is yet unknown ; as they are dif- 

 cerned of all fizes, from thofe which are barely invifible to the 

 naked eye, to fuch as refift the action of the microfcope, as the 

 fixed ftars. do that of the telefcope, and with the greatefl powers 

 hitherto invented, appear only as fo many moving points. 



The fmalleft living creatures our inflruments can mew, are 

 thofe that inhabit the waters ; for though animalcula, equally mi- 

 nute, may fly in the air, or creep upon the earth, it is fcarce 

 poffible to get a view of them ; whereas, water being tranfparent, 

 and confining the creatures within it, we are enabled, by applying 

 a drop of it to our glafles, to difcover with eafe a great part of 

 it's contents. 



It has been long known, that if feeds, herbs, or other vegeta- 

 ble fubftances, are infilled in water, the water will foon be filled 

 with an indefinite number of little animals. We find them, in 

 general, moving in all directions with equal eafe and rapidity ? 



3 K fome- 



