60 GENERAL BIOLOGY 



produced by the action of the cilia. What is the general 

 direction over the surface of the body? In the mouth 

 groove? 



2. Defense. Run some dilute picric acid under the cover 

 and observe the trichocysts which are thrown out. In a 

 drawing show the trichocysts and the cilia. 



3. Nutrition. (a) Ingestion of food. Place some para- 

 mecia on a slide with a small amount of powdered carmine 

 in water and watch the formation of a food ball in the gullet, 

 and the way in which it is taken into the body. When it 

 gets into the body it becomes a food vacuole. 



(6) Nature of the Food. Study the contents of the food 

 vacuoles found naturally in the body and determine, if 

 possible, what the Paramecium feeds upon, especially 

 whether it is plant or animal food. 



(c) Digestion. Observe the changes in form, size and 

 amount which take place in the food as it passes through 

 the body. Are there changes in the food vacuole? What 

 do they mean? 



4. Circulation of the Protoplasm. Watch the food vacuoles, 

 especially after having added the carmine, and see whether 

 they change their position in the body. If there is any 

 movement make an outline drawing and show by arrows 

 the course of the circulation. 



5. Irritability. What reasons are there for believing that 

 Paramecium is sensitive to external influences? Do they 

 avoid objects? Do they collide with each other in motion? 

 Do they tend to collect in masses? Where? Why? Are 

 they as active at the end of the hour as at the beginning? 

 Why ? Is the animal sensitive to touch or pressure ? 



6. Reproduction. (a) .Fission. This is the usual method of 

 reproduction and consists in the division of the animal into 

 two parts. At what part of the body and in what direction 



