U2 THE OCEAN WORLD. 



state of opacity. Their bodies are more or less globular or ovoid, 

 sometimes fashioned like a shuttle, or curved while growing, sometimes 

 swollen in the middle like an ampulla, or bell- 

 shaped, and flattened into a discoid shape ; 

 some slightly resemble a tadpole, a thimble, a 

 shoe, a rose-bud, a flower, even a seed. 



The Paramecians have a soft flexible body, 

 usually of oblong form, and more or less de- 

 pressed. They are provided with a loose reticu- 

 lated covering, through which issue numerous 

 vibratile cilia, arranged in a regular series. 

 They were known to the older naturalists ; and 

 it is in this group that organization is carried 

 to the highest perfection it attains among the 

 Infusoria. 'The Paramecium possess, besides 

 their reticulated and contractile tegument, cilia 



Fig 37. Cothurnia pyxidiformis -. n . , 



(Udckem). disposed in such a manner as to serve at once 



for locomotion, for prehension, that is, for seizing its food, and as a 

 means of respiration. They are furnished with a mouth, at the bottom 

 of which the whorl excited by the cilia determines, according to 

 Dujardin, the hollowing out of a cavity, formed after the manner of 



a cul-de-sac, and also the formation 

 of vacuoles with permanent parti- 

 tions, in which are enclosed the 

 substances which the animalcules 

 have swallowed along with the 

 water. 



The Paramecium are propagated 

 by spontaneous division, as already 

 described. They abound, as we 

 have said, in stagnant water, or in 

 pure water which is occupied by 

 aquatic plants, sometimes in such 



Fig. 38. Parameciura bursaria .... . . , , , 



(Pritchard). prodigious quantities that they be- 



come troublesome. They occur also in flower vases where the water 

 is not frequently renewed. 



The species of this genus have an oblong compressed body, with 

 an oblique longitudinal fold, directed towards the mouth, which is 



