CHAPTER II. 



Infusoria, 

 Continued. 



This brief sketch of the history of the Vorticella will serve 

 to illustrate that of the whole class of Infusoria ; as the 

 facts, at least the earlier ones, with slight modifica- 

 tions, are common to all. The round bodies resem- 

 bling beads, which we mentioned as scattered in the 

 interior of the bell, are characteristic of the whole of 

 these animals. Professor Ehrenberg considers them to 

 be so many stomachs, connected either with the com- 

 mon mouth, or with an intestinal canal which runs 

 through the body. To this conclusion he came by pro- 

 secuting a series of curious and ingenious experiments. 

 By mixiDg coloured substances, such as carmine or indigo, 

 with the water in which the animalcules were living, he 

 found that they readily imbibed them, and that the 

 colouring matter was presently accumulated in these in- 

 ternal vesicles, which then appeared crimson or blue, 

 according to the pigment employed. .Hence he applied 

 the name Polygastrica to the class, a term which would be 

 as appropriate as it is significant were it quite certain 

 that his conclusions legitimately follow from his premises. 

 But later naturalists have doubted that these vesicles are 



B 



