42 



THE ANIMALS AND MAN 



The Bell Animalcule (Vorticella sp.). — Technical Note. — 

 Specimens of Vorticella may usually be found in the same water with 

 Amosba and Paramcecium. The individuals live together in colonies, 

 a single colony appearing to the naked eye as a tiny whitish mound-like 

 tuft or spot on the surface of some leaf or 

 stem or root in the water. Touch such a 

 spot with a needle, and if it is a Vorticellid 

 colony it will contract instantly. Bring bits 

 of leaves, stems, etc., bearing Vorticellid 

 colonies into the laboratory and keep in a 

 small stagnant-water aquarium (a battery- 

 jar of pond- water will do). 



Examine a colony of Vorticella in 

 a watch-glass of water or in a drop 

 of water on a glass slide under the 

 microscope. Note the stemmed bell- 

 shaped bodies which compose the 

 colony. Each bell and stem to- 

 gether form an individual Vorticella 

 (fig. 14). • How are the members of 

 the colbny fastened together? Tap 

 the slide and note the sudden con- 

 traction of the animals; also the 

 details of contraction in the case of 

 an individual. Watch the colony 

 expand; note the details of this move- 

 ment in the case of an individual. 



Make drawings showing the col- 

 ony expanded and contracted. 



With higher power examine a 

 single individual. Note the thick- 

 ened, bent-out, upper margin of the 

 bell. This margin is called the 

 peristome. With what is it fringed? 

 The free end of the bell is near- 

 ly filled by a central disk, the epis- 



FiG. 14. V orticella sp.; one 

 individual with stalk 

 coiled and one with 

 stalk extended; note 

 the peristome, epis- 

 tome, vestibule, nucle- 

 us, contractile vesicle, 

 food particles, etc. 

 (Greatly magnified; 

 from life.) 



