465 



Microscopical Essay s. 



can be obferved of detached and feparated parts becoming what 

 is called microfcopic'animalcula. Indeed, it is furprizing that 

 Mr. Needham fhould ever take the filaments of the moiftened 

 grains for any thing elfe than a vegetable production, a true fpe- 

 cies of mouldinefs. 



On the 25th of May, Fahrenheit's thermometer 70 0 , Mr. 

 Ellis boiled a potatoe in the New River water till it was reduced 

 to a mealy confiftence. He put part of it, with an equal propor- 

 tion of the boiling liquor, into a cylindrical glafs vefTel, that held 

 fome thing lefs than half a wine pint, and covered it clofe imme- 

 diately with a glafs cover. At the fame time he fliced an unboiled 

 potatoe, and, as near as he could judge, put the fame quantity 

 into a glafs veflel of the fame kind, with the fame proportion of 

 New River water not boiled, and covered it with a glafs cover, 

 and placed both veffels clofe to each other. 



On the 26th of May, twenty- four hours afterwards, he ex- 

 amined a fmall drop of each by the firft magnifier of Wilfon's 

 microfcope, whofe focal diflance is reckoned at T v part of an inch ; 

 and, to his amazement, they were both full of animalcula of a 

 * linear fliape, very diftinguifhable, moving to and fro with great 

 celerity ; fo that there appeared to be more particles of animal 

 than vegetable life in each drop. 



This experiment he repeatedly tried, and always found it to 

 fucceed in proportion to the heat of the circumambient air ; fo 

 that even in winter, if the liquors are kept properly warm, at 

 leaft in two or three days the experiment will fucceed. 



The 



