100 



TEXTBOOK OP ZOOLOGY 



Behavior 



This animal is an active swimmer and necessarily shows ready 

 response to environmental factors. Its behavior consists of its 

 spiral course in locomotion, avoiding reactions, responses to food 

 material, contact and other minor reactions. Its reactions to stimuli 

 are somewhat similar to those described for Amoeba; however, it 

 seems not to be affected by ordinary light. It reacts either posi- 

 tively or negatively to contact, change of chemical constitution, 

 change in temperature, to gravity, and to electric current. The re- 

 sponse to contact is positive, negative to ultraviolet light, negative 



a 



——7 = 9 ^ ^ :; ^ - s 1 ^ / /^ 



' ^ 9 " 





JS' 



19- 



rj,-?-.V."."-:-t;^-_f ,-_.' . . 



pSn^-";Y=iV;-".-' 



Be- 



ss- 



Fig. 42. — Reactions of paramecia to temperature, a, Paramecia are in a 

 trough with temperature at 19° C. uniformly through the water. The animals are 

 generally scattered. In & the temperature is held at 26" C. at the left end and 

 38° C. at the other. The animals are collected in the end of lower temperature. 

 In c, the temperature is 25° C. at one end and 10° C. at the other, and the Para- 

 mecia are congregated in the region of higher temperature. (From Jennings, 

 Hehavior of the Lower Organisms, published by The Columbia University Press.) 



to sodium chloride, positive to weak acetic acid, and positive to the 

 negative pole of a weak, galvanic electric current. The optimum 

 temperature for Paramecium ranges between 24° and 28° C. (71° 

 P.). Gravity causes the anterior end to point upward, and when 

 placed in moving water, the animals will swim upstream. If Para- 

 mecium comes in contact with a solid object when it is moving, it 

 will back away, swing on its posterior end to a slightly different 



