THE CELL. 49 



THE SLIPPER ANIMALCULE. 



The Slipper Animalcule may be found in hay infusion. It is a 

 unicellular animal, provided with a cell-wall, and reproduces by 

 normal fission. 



Classification: 



Kingdom Animal. 

 Series Protozoa. 



Sub-kingdom Protozoa. 

 Class Infusoria. 

 Order Ciliata. 



Genus Paramoecium. 



Species Paramcecium candalum. 



Life History and Morphology. The Slipper Animalcule is a sin- 

 gle cell provided with cell-wall, protoplasm, a double nucleus 

 (macro-nucleus and micro-nucleus), two contractile vesicles, and 

 food and water vacuoles. It receives its food through a mouth. 

 Leading to the mouth is an cesophagus which terminates near the 

 middle of the body surface in a depression called the vestibule. This 

 depression, as well as the whole surface of the cell, is provided with 

 cilia. The cilia are minute, hair-like, protoplasmic projections 

 which by their rapid motion enable the animal to move from place 

 to place. Excretion is accomplished by means of an anal spot. This 

 is not a permanent opening, but a thin place in the cell-wall through 

 which the excretions are forced by means of the contractile vesicles. 

 Reproduction occurs by normal fission, and is accomplished by the 

 division of the nucleus and protoplasm into two halves and the con- 

 striction of the cell-wall. 



Laboratory exercise No. 10. Slipper Animalcule. Examine some of 

 the scum which forms on the surface of hay infusion. Examine with 

 the high power, and, having- found a specimen of the animalcule in a 

 quiet condition, observe the following structures: Cell- wall, cilia, vesti- 

 bule, oesophagus, mouth, protoplasm, double nucleus, food masses, the 

 water vacuoles, and the contractile vesicles. Make a drawing to illus- 

 trate the structures thus named. 

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