THE PHYSIOLOGICAL UNIT AND DIVISION 

 OF LABOR 



PROBLEM XXV 



To study a one-celled anim,al, in order to understand 

 better tJie unit of animal structures. 



Apparatus. Pipette, glass slides and cover glasses, and com- 

 pound microscope, charts showing methods of reproduction, 

 etc., hay infusion. 



Method. Place some of the cloudy material from an infu- 

 sion of hay or grass on a glass slide, cover with a cover glass, 

 and study with low power of the microscope. 

 (Look for paramcecia.) 



a. In its Relation to its Surroundings 

 1. REACTIONS TO STIMULI 



Observations. 1. Look carefully for small 

 whitish animals moving rapidly about 

 much as shown in Figure 41. Do they move 

 with any certain end first ? 



2. What shape has one of these animals ? 



3. Are they able to bend their bodies ? 



4. Do they seem to be able to avoid any 

 obstructions ? 



5. Do they seem to congregate in any 

 places in particular ? 



6. What seems to be the method of loco- 

 motion ? 1 Note. Here refer to Figure 41, 

 and find the cilia, or fine vibratory hairlike 

 structures. 



instructor may demonstrate cilia if time permits, although it is not 

 considered necessary. 



140 



FIG. 41. Diagram 

 of a paramoecium. 

 F. V., food vacuole ; 

 C. V., contractile 

 vacuole ; M, mouth ; 

 N, nucleus. (After 

 Sedgwick and Wil- 

 son.) 



