Microscopical Essays. 



Vorticella acinofa, fimplex, globofa, granis nigricantibus, pedtui- 

 eulo rigido. Muller Animal Infuf. p. 31$, 



We often find in divers places, upon water,; 'plants, and other 

 bodies in the water, a whitifh fubftance, that looks like mould ; 

 plants, pieces of wood, mail (hells, Sec. are often entirely cover- 

 ed over with this fubftance. If we examine any of'thefe by the 

 microfcope, we fhall find fuch motions as will induce us to think 

 them an affemblage of living animals, minute bodies, feverally 

 fixed to the extremities of fmall ftems, or pedicles, many of 

 which are often fo united as to form together a fort of branches, 

 or clufters, from whence they have been termed cluttering 

 polypes, or des polypes en bouquet. 



Thefe clufters are larger or fmaller, according to the fpecies of 

 the vortieellae which form them, and according to the con- 

 currence of many other circumflances. To get a clear idea of 

 the figure of thefe animals, it is beft to obferve the fmaller cluf- 

 ters, as in the larger they are often rendered lefs diftincl; on 

 account of the number. 



The length of thofe which are reprefented at Fig. 30, is about 

 the 240th of an inch ; they are of a bell-ihape. The anterior part, 

 a c generally appears open, the pofterior part is fixed to a ftem, 

 or pedicle, be; it is by the extremity of this pedicle that the vor- 

 ticella fallens itfelf to any fubftance. It appears in the microfcope 

 of abrownifh colour, excepting at the fmaller end b, where it is 

 tranfparent, as well as the whole pedicle b e. When the anterior 

 part a c is open, a very lively motion may be perceived about it's 

 edges ; and when it prefents itfelf in a particular manner, fome- 

 6 thing 



