360 ZOOLOGY 



nuclei in the living animal, run a 5% or 10% aqueous solution of 

 methyl green under the cover-glass by placing the solution at one 

 edge of the cover-glass and drawing it under by filter paper placed at 

 the opposite edge. To stain the plasma, a little iodine may be added ; 

 this will kill, with explosion of trichocysts. 



DRAWING 

 {From observations on several individuals) 



Whole animal, showing shape of body, cilia, vestibule, food- 

 globules, non-contracting vacuoles, contracting vacuoles, nucleus, 

 trichocysts. x about 200. 



OBSERVATIONS ON THE LIVING ANIMAL 



Each student should be provided with the following: (1) vial 

 containing beef extract ; (2) vial containing finely powdered car- 

 mine in water ; (3) common salt ; (4) pipette ; (5) filter paper. 



1. Is the protoplasm in the body of Pararnecium quiet or moving? 



2. Place Pararnecium in a drop of the gelatine solution. Cover 

 with cover-glass. Run carmine-water under the cover-glass; select a 

 quiet individual and observe how the carmine grains pass by it. 

 Indicate by arrows placed outside the periphery of the drawing the 

 direction of movement of the carmine. What do you infer concern- 

 ing the movement of the cilia? Do the grains whirl as much about 

 a moving individual as about a quiet one ? Can you explain ? Why 

 are not all the Paramecia carried off by the current when carmine is 

 run under the cover-glass ? 



3. Place upon a clean glass slide a drop of water containing Para- 

 mecia. When they are uniformly distributed, put a few grains of 

 common salt in the centre of the drop. After a few seconds observe 

 and draw the distribution of the organisms. How is the result to 

 be interpreted? 



4. Place upon the glass slide a drop of water containing Paramecia; 

 by means of a pipette (drawn to a fine point), add a drop of % to 

 T ^ % acetic acid ; after two or three minutes draw the distribution 

 of the Paramecia. How do reactions to acids and to salts compare ? l 



!See H. S. Jennings, American Journal of Physiology, May, 1899, and 

 American Naturalist, May, 1899. 



