INFUSORIA. 187 



undulatory mode of swimming.* Some, as the 

 Gonium, have an angular, others, as the Kol- 

 poda, a waving outline. Some, as the Urceolaria, 

 present the likeness of a bell or funnel, and 

 appear to be analogous to the Vorticella, in 

 which genus they should probably be included. 



Forms still more irregular are exhibited by 

 other infusoria. Of these the most singular is 

 the Proteus (Fig. 78), which cannot, indeed, be 



said to have any determinate shape, for it seldom 

 remains the same for two minutes together. It 

 looks like a mass of soft gelly, highly irritable 

 and contractile in every part ; at one time wholly 

 shrunk into a ball, at another stretched out into 

 a lengthened ribbon ; and again, at another 

 moment, perhaps, we find it doubled upon itself 

 like a leech. If we watch its motions for any 

 time, we see some parts shooting out, as if sud- 



* Animalcules referable to this genus are met with in great 

 numbers in blighted wheat, (Fig. 2, p. 62) in sour paste, and 

 in vinegar which has lost the whole of its alcohol. In this last 

 fluid they sometimes attain so large a size as to be visible to the 

 naked eye. 



