52 ASA A. SCHAEFFER. 



pseudopod was thrown out on the right, through which the 

 ameba finally moved off. The ameba was then shifted so that 

 the light lay on the right 63. The ameba turned to the left 

 and moved on. The ameba was again shifted with the light 

 lying on the left 65. As the ameba moved forward a small 

 pseudopod which was thrown out on the left moved directly 

 into contact with the light. The next four experiments 69-93 

 all show that the beam of light was sensed before the ameba came 

 into contact with it, and also that the light produced more or less 

 definite positive behavior, followed by indifferent or negative 

 behavior. 



A beam of red light was projected in the path of another 

 protens 94. A pseudopod was thrown out toward the light. 

 After it came into contact with the light 97 the ameba 

 moved away through a pseudopod thrown out on the left 99. 

 The ameba was then shifted with the beam of light on the left 



101. The ameba moved forward, then turned slightly to the 

 right 104. A small pseudopod was then sent out toward the 

 red light 107 but after covering half the distance it was re- 

 tracted while a pseudopod was thrown out on the same side, but 

 further forward. From this pseudopod still another was sent 

 out on the left. The ameba thus partly encircled the red light. 

 The ameba was shifted again with the red light lying in front of 

 it in. The ameba threw out a pseudopod on the right and 

 passed on 111-113 but when the tip of the main pseudopod 

 extended beyond the light, it broke up into four pseudopods 

 115 of which the left posterior ultimately became the main 

 pseudopod through which the ameba moved away. 



Another proteus was then brought into the field with a beam 

 of red light lying to the right 120. The ameba moved on a 

 short distance, then threw out two pseudopods on the right 122 

 one of which moved into contact directly with the red light 



-125 but which was retracted as the ameba moved on. The 

 ameba was then shifted with the light lying on the left 125. 

 Pseudopods were sent out on both sides but the one on the right 

 finally became the main one leading the ameba away. The 

 ameba was again shifted with the red light lying on the right 

 128. A pseudopod was thrown out on the right directly toward 



