LABORATOEY WORK, XVI 361 



5. Under a moderate power observe the reactions of Paramecium 

 when it comes to the salt or acid. 



TOPICS FOR FURTHER STUDY 



1. How the Infusoria get into the aquarium. 2. The habitat and 

 food of Paramecium. 3. Allies of Paramecium : Stentor, Vorti- 

 cella, Carchesium, Euglena, the Suctoria, Amoeba, the Gregarinidse. 

 4. Economic importance of Amoeba and the Gregarinidae. 5. Repro- 

 duction of Paramecium. 



XVI. SMELT (Osmerus mordax} 



Various other bony fishes may replace the smelt, e.g. brook trout 

 (Salmo fontinalis), lake herring or white fish (Coregonus), perch 

 (Perca). 



DRAWINGS 



1. Whole animal, from left side, fins extended, showing number of 

 fin rays, position of lateral line, mouth, tongue, teeth, nostrils, anus, 

 urinary openings, x 1 to 2. 



2. Side view of a few trunk segments as seen after removal of 

 skin. 



3. Ventral view of head, gill cover removed, mouth open, probes 

 passing from mouth through each of the gill slits. Show teeth and 

 slime-glands, x 2 to 3. 



4. Dorsal view of head, showing, when possible, form of brain seen 

 through brain case, x 2. 



5. Cross-section (5 mm. thick) of whole animal in front of anus 

 and behind dorsal fin. Name organs as instructed by teacher. 



6. Lateral view of vertebra, from the section mentioned in 4, 

 isolated by boiling. 



QUESTIONS ON EXTERNAL ANATOMY 



1. How many rows of scales are there above the lateral line ; how 

 many below ? 



2. How many segments behind the head? Is this number constant? 

 (Compare with two other individuals.) 



