XIII. SINGLE-CELLED ANIMALS CONSIDERED AS 

 ORGANISMS 



Problems. — To determine : 



(.a) Sow a one-celled animal is influenced by its environ- 

 ment. 



ib) How a single cell performs its function. 

 (c) The stnooture of a single-celled animal. 



Laboratory Shqqestions 



Laboratory study. — Study of paramoecium under oompound micro- 

 soope in its relation to food, oxygen, etc. Determination of metiiod of 

 movement, turning, avoiding obstructions, sensitiveness to stimuli. Draw- 

 ings to illustrate above points. 



Laboratory demonstrations. — Living paramoecium to show structure 

 of cell. Demonstration with carmine to show food vacuoles and action 

 of ciUa. Use of charts and stained specimens to show other points of 

 cell structure. Laboratory demonstration of fission. 



To THE Teacheb. — With the introduction given by the previous chapter, it is 

 easy to demonstrate some of the reactions of a single-celled animal, and compare 

 them with those of a single-celled plant. The structure of a cell and its various 

 functions as an organism make this chapter of great interest to all pupils, espe- 

 cially as the wonders of the world of the microscope are placed at their disposal. 



Problem 112: To study a one-celled animal in order to 

 understand better ia) its reactions to stimuli; ib) the cell as a 

 unit of structure. 



Materials. — Hay infusion, pipette, glass slides, cover glasses, 

 and compound microscope, Kny or Leukart charts. 



Method. — ^ Remove, by means of a pipette, a few drops of the 

 whitish scum on the top of the hay infusion. This scum contains^ 

 great numbers of paramoecia (a one-celled animal). Mount on a 

 slide with a little spirogyra or other greeil alga. After allowing 

 slide to stand for a few moments, examine under the low power. 



132 



