VORTICELLA » 



1. Mount a drop of water containing numerous specimens of Vorticella, 

 together with a little powdered carmine, and examine with the low power. 

 Make a drawing of a small group of the animals attached to a piece of 

 debris. 



2. Study the preparation with the high power and note that the general 

 shape of the organism resembles a bell, projecting from which is a long 

 contractile stalk. Note the thin, outer pellicle, the ectoplasm, and the 

 endoplasm. Determine how and where the particles of carmine are taken 

 into the body and identify the gastric vacuoles containing the carmine 

 particles. 



3. Identify the following structures : (a) the peristome, or rounded 

 rim, at the large end of the bell ; (b) the disc, or elevated, plate-like area, 

 included within the peristome and filling the large end of the bell ; (c) the 

 vestibule, or depression, between the disc and the peristome ; (d) the 

 mouth, opening into (e) the gullet which is a slender tube leading from 

 the vestibule into the endoplasm of the body ; and (/) the contractile 

 vacuole. Determine what parts of the body bear cilia. Study the 

 contractions of the stalk. Examine your preparation and see if you can 

 find any stalkless, free-swimming individuals and, also, any animals under- 

 going division with two immature individuals attached to the same stalk. 



4. Make a drawing about 3 inches long showing the general structure 

 of the organism and as many as possible of the details mentioned above. 



5. Add a little acetic carmine to your preparation, which will kill and 

 stain the animals, and then note : (a) the long, U-shaped macronucleus ; 

 (b) the small, round micronucleus ; (c) the stalk consisting of a sheath 

 continuous with the pellicle of the bell, and surrounding the axial fila- 

 ment composed of the individual contractile elements (myonemes). Add 

 these structures to your previous drawing. 



6. Mount and examine a few drops of water containing various other 

 common species of Infusoria, such as the flattened, creeping forms (Oxy- 

 tricha, Stylonichia, Euplotes) or the larger tubular forms (Stentor or 

 Spirostomum). A particularly interesting type is Didinium, which feeds 

 almost exclusively on Paramecium. Try to see them feeding if possible. 

 Identify the various species present and compare their general structure 

 and activities with those of Paramecium and Vorticella. (W. f. 26.) 



» B. pp. 48-51. 

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