CLASS INFUSORIA. 



FIG. 11. 



Vor ti eel' la neb u fif' e ra, 

 or Sell - animalcule. C, 

 Row of long Cilia encir- 

 cling the disk or lid, L. 

 S, Stem. Other letters 

 same as in previous fig- 

 ures. Note the elongated 

 nucleus. (Greatly en- 

 larged.) 



Bell Animalcules (an i mal'kulz). When viewed under a 

 microscope each single bell is found to have a ciliated 

 lid with a mouth-opening* under one portion of its cir- 

 cumference. In the body can often be 

 seen an elongated nucleus and one or 

 two pulsating vacuoles. On being irri- 

 tated, the stems of the small bells 

 contract, bringing the entire colony 

 against the object to which it is at- 

 tached. 



During the warm weather, when the 

 pools dry up, these ciliated animals 

 draw in their cilia and enter an en- 

 cysted stage ; a few days of moisture, 

 however, will serve to burst the wall of 

 the cyst, when a multitude of new Vor- 

 ticellse swim forth. 



While considering the members of this first Branch 

 of the animal kingdom, though dealing with animals con- 

 sisting of but a single cell, we have found them capable 

 of motion, of sensation, of finding, securing, digesting, 

 and assimilating food, and of reproducing other animals 

 similar to themselves. Thus, in their humble position, 

 they are endowed with powers resembling, though not 

 equaling, those of the higher forms. 



All other animals are made up of aggregations of 

 cells, and are thus of such a size as to be generally 

 appreciable to the unaided eye. This many-celled struct- 

 ure of the remaining Branches has given to them the 

 name of Metazoa (met a zo'a). 



* In many parasitic ciliata, as in the parasites of the higher animals, the 

 mouth parts are wanting, and the animal receives its nutriment hy imbibition, 

 no solid food being taken. 



