THE BIOLOGY OF THE CELL 



3. The nucleus.— What is its position? Shape? 



Size ? Is it visible in each specimen ? Is it al- 

 ways seen in the same place when visible at 

 aU ? If not plainly to be seen apply a drop of 

 dilute iodine, of one per cent, acetic acid, or 

 of one per cent, acetic acid carmine to one edge 

 of the cover-glass, and allow the stain to run 

 under the cover. Watch the effect on the other 

 parts of the animal also. If the stain be used, 

 fresh specimens must be prepared before going 

 on with the study of the contractile vacuole. 

 Do you find more than one nucleus? Is there 

 a nucleolus ? In stained specimens the nucleus 

 will appear darker than the surrounding proto- 

 plasm. 



4. The contractile vacuole.— Position? Shape? 



Are position and shape constant in the same 

 and in different specimens? Does the vacuole 

 have any visible contents ? Do you find speci- 

 mens having more than one contractile vacuole ? 

 If there are several vacuoles, are they aU con- 

 tractile ? 

 Make a drawing to illustrate the structure of Amceba. 



PHYSIOLOGY 



, Movements. — What kind of motion does Ammba ex- 

 hibit ? Is the motion continuous ? Eegular ? 

 Does the body change shape when moving? 

 What part of the body is used to produce move- 

 ment ? Watch the manner in which a pseudopo- 

 dium is formed. Is it always from the same part 

 of the body? What part does the ectosarc play 

 in the process of moving ? Endosarc ? Does the 

 endosarc extend into the pseudopodium ? Study 



