Examples of Pupils* Work 177 



i. INTRODUCTION, a. Classification. The Paramecium 

 or slipper animalculi is a ciliated infusoria which exhibits 

 a considerable amount of differentiation within the limits 

 of a single cell. It belongs to the kingdom of protozoa, 

 class infusoria, and order ciliata. The kingdom of protozoa 

 represents the lowest branch of animal life. It is charac- 

 terized by the fact that after fission each cell becomes a 

 distinct individual. The infusoria is the most highly 

 specialized of all protozoa showing a differentiation of 

 protoplasm unattained by any other member of this group. 

 The Paramecium is one of the largest and most common 

 of the infusoria. The ciliata are characterized by the 

 possession of hair-like processes called cilia, which are 

 present during young and adult stages. 



b. Habitat in nature. The Paramecium is found in 

 ponds and ditches amongst decomposing vegetable matter. 

 It is also found in multitudes in hay infusion or water 

 containing decomposing remains of Nitella and other 

 water-plants. It is found in both fresh and salt water. 



c. How cultivated. Paramecium may be cultivated by 

 filling a can with water; then place a small handful of 

 pieces of hay or dead moss in the water and allow it to 

 stand in a warm place for about a month. After a few 

 days a white film will appear upon the surface of the water 

 and if the lower edge of this film be examined where it 

 touches the can great numbers of rapidly moving white 

 animals may be seen. Large quantities may be reared by 

 collecting con ferae and water-seeds in summer weather, 

 placing them in a jar of warm water covered by a glass 

 and leaving them to rot. 



2. MORPHOLOGY, a. Form, size, and general appearance. 

 The Paramecium has an elongated, somewhat flattened, 

 soft, flexible, transparent body, about y^-g- of an inch in 

 length, with a rounded anterior end and somewhat pointed 

 posterior end, the maximum breadth being near the latter. 



When viewed from above and below it is oval and some- 

 what slipper-shaped in side view. The posterior end is 

 bluntly pointed and forms the toe of the slipper, while the 

 anterior end is rounded and twisted so that the outline of 

 one side of the anterior end is bent into a shape somewhat 

 like a figure eight. As this side is generally uppermost 



