64 STRUCTURAL AND SYSTEMATIC ZOOLOGY 



of freeing themselves from their stalk and swimming 

 away to another place where the new colony is to be 



started. Thus there is 

 shown among these sim- 

 ple organisms the differ- 

 entiation of parts which 

 is one of the character- 

 istic features of the higher 

 forms of animal life. 



The cilia are used for 

 locomotion and for ob- 

 taining food, which, ex- 

 cept in the parasitic 

 / species, is in the form 

 of solid particles, consist- 

 ing of bacteria and micro- 

 scopic plants and animals, 

 or of minute fragments of 

 animal and vegetable ma- 

 terial. All of the ciliata 

 which ingest solid food have a permanent mouth open- 

 ing. Tentaculifera 

 suck through their 

 tentacles the soft ma- 

 terial composing the 

 bodies of their prey. 

 The cilia are uni- 

 formly arranged over 

 the body, as in Para- 

 mecium, or are re- 

 stricted to definite 

 regions, as in Vorti- 

 cella. In either case 

 there may be variations in their form, size, and func- 

 tion. Reproduction is by division and by budding, 



FIG. ii. Vortice lla : a, showing stages of 

 fission, and b, internal structure; d, cili- 

 ated disk ; g, gullet ; , nucleus ; c, con- 

 tractile vacuole ; f, food vacuole. Much 

 magnified. 



FIG. 12. Actneta, animal in its lorica, /, showing 

 suctorial tentacles and nucleus, n, with contractile 

 vacuole. Only a small part of the stalk is 

 shown. Magnified, 



