10 THE BIOLOGY OF THE CELL 



heat a small glass rod in the flame of an alcohol 

 lamp, and touch the heated rod to the cover-glass 

 in the neighborhood of the animal. What re- 

 sult? 



d. Reproduction. — Look for specimens in the process of 

 fission or division. If one be found, note how the 

 process takes place and the length of time re- 

 quired. Compare the two resulting bodies as to 

 size and structure. Which is the parent ? Is the 

 process preceded by sexual union? How is one 

 sex distinguished from the other ? 



General Questions. — How does Amosba protect itself 

 from its enemies ? Kill an Ammba by crushing it under 

 the cover-glass. What changes take place in the proto- 

 plasm ? Why does not the protoplasm of a living AmcB- 

 ha go through the same changes ? Do the granules of 

 a crushed AnKxla continue to move? How does this 

 movement (if any) compare with that observed in the 

 living Amceba % Compare with the crushed and with 

 the living Amceba a drop of the white of egg and a small 

 piece of gum-arabic, both In water. What differences 

 can you detect ? How do you explain them ? Does 

 Ammba have any organs ? Why ? 



Example 3. — Tlie Slipper Animalcule (Paramecium Sp.) 



Material. — Specimens may almost always be found 

 in water which contains a considerable amount of de- 

 caying vegetable matter. They are usually abundant 

 around the decaying stalks and leaves of pond-lilies. 

 They may be raised in enormous number in the course 

 of a week or two by placing in a warm, dark place a 

 fruit -can containing water in which are dead fresh- 

 water algae or other decaying vegetable substance. 



