58 ASA A. SCHAEFFER. 



Yellow Light. -A beam of yellow spectral light was projected 

 straight ahead of a proteus 271. The ameba moved on without 

 any definite change of behavior and passed over the beam of 

 light. The change in the direction of movement 275-277 



indicates that the yellow beam had a disagreeable effect after 

 the ameba came into contact with it. When the ameba was 

 shifted 278 the tip of the main pseudopod turned to the left 



a negative reaction continued from the previous experiment. 

 But while passing the beam of light the negative condition 

 gave way to a positive as is shown by the turning of the tip of the 

 ameba toward the light 282. A pseudopod was then thrown 

 out on the left on the convex side, and from this one another on 

 the left through which the ameba moved on, again a negative 

 reaction. The ameba was shifted again 285 with the yellow 

 light ahead. The ameba turned sharply to the right, but as it 

 passed by the light a pseudopod was thrown out on the left 

 directly toward the light 287. This pseudopod became the 

 main one through which the ameba flowed on over the light. 

 As the ameba came nearly into contact with the light, a pseudo- 

 pod was thrown out on the right 290 an indication of a nega- 

 tive reaction, but it was soon retracted. 



To summarize: Amebas respond positively, negatively or in- 

 differently to beams of yellow spectral light. As far as my ex- 

 periments go, yellow light has about the same effect as red or 

 blue or the other spectral colors which have so far been considered. 

 Orange Light. A beam of orange light was projected to the 

 left of a proteus 294. The ameba turned to the left and moved 

 directly into contact with the light. When the ameba came into 

 contact with the light, a pseudopod was started on the right, but 

 it was soon retracted and the ameba flowed on over the light 

 without further change of behavior. The ameba was then shifted 

 with the orange light on the left 301. The tip of the ameba 

 turned to the left, then broke up into two pseudopods of which 

 the left one turned still further to the left and finally became the 

 main pseudopod through w r hich the ameba flowed away. The 

 ameba was shifted again with the orange light slightly to the 

 right 306. A pseudopod which was thrown out on the right 

 elongated as it turned to the left. When the tip of the pseudo- 



