156 Of Animalcula in Fluids, 
ler. They rub their eggs with their tail, which as it 
enters into, and goes out from the body, turns from one 
fide to the other with a great deal of pliablenefs; thofe 
eggs which are full, appear hanging down, and are very 
regular and bright, thofe that are empty are feen quite 
fiat, and of an oval form, and more tranfparent than the 
others, and although empty, their mothers carry them 
alraoft always fattened to their breech, as at fig. 286. 
Two of thefe eggs were feen in the body of one of thefe 
animalcules, and appeared as at G G, fig. 288. 
Thefe animalcules are a delightful objectt for the mi- 
crofcope, particularly when they tumble over head and 
tail, becaufe they do it dextroufly. Some turn them- 
felves circularly, as much on one fide as the other, and 
about the point F, which is the center of gravity of their 
bodies. 
Infufion of the bark of an oak. 
S O M E of this bark being put into' cold water, the 
fifteenth of December, and examined feveral times 
for the fpace of a whole year, during which time the fol¬ 
lowing animalcules were difcovered. The firft was called 
a tortoife with an umbelical tail, fig. 290. This infedfc 
ttretches out and contracts itfelf very eafily, fometimes 
affuming a round figure, which it does not retain above 
a moment; then opening its mouth to a furprizing 
width, forms nearly the circumference of a circle ; its 
lips are furnifhed with hairs, whofe motion is very 
pleafant, becaufe it obliges fome of the adjacent little 
bodies, to precipitate into its ftomach, where that which 
is fit for food remains, while the other is repelled with 
great velocity; its motion is very furprifing and fin- 
eular. 
