Marvels of Pond-Life. 21 



elegant instrument called a parabolic illuminator, which 

 need not be described. 



Different specimens and species of Vorticella vary in 

 the length of their bells from one three or four 

 thousandth to one hundred and twentieth of an inch, 

 and when they are tolerably large, the dark ground 

 illumination produces a beautiful effect. The bells 

 shine with a pearly iridescent lustre, and their cilia 

 flash with brilliant prismatic colours. 



The Vorticellina belong to the upper division of the 

 Protozoa — the ciliata, or ciliated animalcules, and they 



Vorticella microstoma, showing Vorticella microstoma, the en- 

 alimentary tube, ciliated mouth, cysted animal protruding through 

 and formation of a gemma at the a supposed rupture of the tunic, 

 base, 300 linear.— Stein. 



have a mouth, an oesophagus, and an orifice for the 

 exit of their food. 



Many observers usea to ascribe to those creatures a 



