PROTOZOA 143 



Vorticelia Campanula Ehrenberg 



Self -maintenance. Vorticelia (Fig. 62, I) is to be found 

 in fresh- water ponds and ditches attached to some object by 

 a slender stalk. The specific name, campanula, refers to the 

 shape of the body, which resembles a dinner-bell with a very 

 long handle. Around the distal margin of the bell there is a 

 row of cilia. These by their continual beating create a 

 vorfcex in which the water is drawn toward the mouth 

 hence the generic name, Vorticelia. 



This little protozoan feeds on minute particles brought 

 to it in the currents created by the cilia. If unsuccessful 

 when drawing water from one source, it jerks back by con- 

 tracting and coiling the stalk, and then stretches out in a 

 new direction, thus increasing its chances of finding organ- 

 isms on which it may feed. There are little contractile 

 strands passing from one end of the stalk to the other, and 

 these are just as much specialized for contraction as the 

 fibrils in the muscle cells of a vertebrate. Food particles 

 enter the mouth after passing through a short gullet, and are 

 enclosed in a little food vacuole before beginning to circulate 

 in the endoplasm. Undigested food passes out through a 

 definite opening in the pellicle. There is a contractile 

 vacuole near the distal end of the bell, which serves for ex- 

 creting metabolic waste products. The trophonucleus in 

 Vorticelia is large and U-shaped. It thus extends through 

 a considerable part of the interior and can readily control 

 metabolism. 



Self -protection. Vorticelia has few enemies. There are 

 some sporozoans which live within it as internal parasites. 

 Some protozoans and larger animals feed upon it. It cannot 

 run away when set upon; its only method of escape is to 

 shorten the stalk as much as possible and remain quiet until 

 danger is past. 



If the conditions of life are unfavorable in a certain place, 

 a Vorticelia may break loose from its stalk and swim to some 

 better spot, where it forms an attachment and grows a new 



