Arcellina.] THE INFUSORIA. 171 



process colourless. In March, 1835, says Ehrenberg, 

 " I first observed hundreds of these creatures in a glass 

 of water, which had stood throughout the winter, in com- 

 pany with some specimens of the Microsterias. Previ- 

 ously to discovering these, the Amoeba verrucosa had 

 been abundantly generated ; and, after their discovery, 

 Arcella hyalina. The creatures were inactive, although, 

 with attentive observation, they might be seen to change 

 their places." Ehrenberg only once perceived the loco- 

 motive organ of the animalcule, situated under one corner, 

 upon which it appeared to rest, and that so firmly, that 

 six out of the eight protuberances of the die-like lorica 

 were visible at the same time. Fig. 95, 96, and 97, repre- 

 sent these creatures in different positions. In the second, 

 the gelatinous variable process is seen projecting from 

 beneath the lorica; in the other two figures, the lorica 

 only is visible. Fig. 98 is a young specimen. Size 

 1-5 70th to 1 -430th. 



