Body ( 



18 



BELL ANIMALCULE. 



SrancTURE — 



Fig. 1. Bell-shaped body with slender stalk for attachment. 



/ Cuticle, a very thin layer of protoplasm investing the body. 

 Disc, covering the mouth of bell and fringed with cilia. 

 Peristome (Gr. 2'eri, around ; stoma, a mouth), the ciliated rim separated from the edge 



of the disc by a groove. 

 Vestibulum (L. an entrance), a depression in the groove where food enters by a 

 permanent mouth. Tiie undigested matter passes out by a temporary anus (L. a 

 vent). 

 QEso'phagus or gullet, leading from vestibule into the soft body-substance. 

 Food-vacuoles, food-particles enveloped in water and dropped off from the end of the 



gullet. 

 Contractile vesicle. 

 \ Curved nucleus, 

 o ( Sheath, a continuation of the cuticle. 



I Axis, the central muscular fibre. 

 Diagram of the Paeamcecium or Slipper Animalcule, a Free-swimming Infusorian — 

 Cuticle and cilia. 



Cortical layer with two contractile vesicles. 

 Body-substance like soft-boiled sago. 



Funnel-shaped mouth opening by a short gullet into body-substance. 

 Anus, merely a temporary opening. 

 Movements — 



Fig. 2. The spirally-coiled stalk, the retracted disc, and the curvcd-in peristome. 

 Figs. 3, 4. Encysted forms — stalked and unstalked. 

 Multiplication — 



Fig. 5. Longitudinal fission ; a bell divides lengthways into two, and the detached portion finally 

 becomes like the original. 

 Eepeoduction — 



Fig. G. a free-swimming bell fuses with a stalked form, producing a single individual; this is the 

 so-called process of conjugation. The attached bell was formerly taken for a bud. (Pos- 

 terior cilia not shown.) 



CLAS.SIFICATION — 



isuh-Kingdom — Protozoa. 



Natural Order — Infusoria, because it possesses an outer layer (ectosarc) provided with cilia and 

 contractile vesicle or vesicles, and an inner substance (endosarc) with nucleus, and usually 

 with a mouth leading into it and an anus leading out. They occur in infusions, hence 

 the name. 



Genus — Vorticella, so named from the vortex caused by the moving cilia. 



Common Name — Bell Animalcule. 



