CHAPTER XV 



BRANCH PROTOZOA: THE ONE-CELLED 

 ANIMALS 



Of this group the structure and life-history of the 

 Amoeba (Amceba sp.) and the Slipper Animalcule (Para- 

 mcecium sp.) have already been treated in Chapter VI. 

 Another example is the 



BELL ANIMALCULE Vorticella sp.) 



TECHNICAL NOTE. Specimens of Vorticella may usually be 

 found in the same water with Amceba and Paramcecium. The 

 individuals live together in colonies, a single colony appearing to 

 the naked eye as a tiny whitish mould-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 together 

 form an individual Vorticella (fig. 8.) How are the 

 members of the colony fastened together ? Tap the slide 

 and note the sudden contraction of the animals ; also the 

 details of contraction in the case of an individual. Watch 

 the colony expand ; note the details of this movement in 

 the case of an individual. 



Make drawings showing the colony expanded and con- 

 tracted. 



With higher power examine a single individual. Note 



75 



