REACTIONS TO LIGHT IN VANESSA ANTIOPA 375 



edge, immediately turned toward the blackened eye and moved 

 along the edge of the beam toward the glower. In the seventh, 

 eighth, and in the twelfth to the nineteenth trials the behavior 

 of the butterfly was essentially the same as in the fifth, but it 

 usually went further in the shaded region before turning toward 

 the glower, this distance varying from 2.5 to 14 cm. After orien- 

 tation, however, it continued to move in all cases fairly directly 

 toward the glower. In the tenth and third trials, the behavior 

 was essentially similar. In the ninth, eleventh, and twentieth 

 the reactions were also very much alike, the organism in each 

 trial curving gradually toward the functional eye, in this way 

 passing beyond the edge of the beam into the shaded region 

 outside, and then coming back to the edge again. On reaching 

 the edge of the beam the second time the butterfly turned niuch 

 more sharply toward the functional eye, thus completing a circus 

 movement and at the same time arriving at the edge of the beam 

 a third time. When this occurred, the insect turned toward the 

 glower and moved along the edge of the beam toward the source 

 of light. 



These reactions in the trials on the first day of the tests show: 

 (1) that Vanessa with but one functional eye tends to turn toward 

 this eye when placed in a beam of light; (2) that it can orient; 

 (3) that orientation does not usually occur in the beam, but 

 does occur either at the edge of the beam or several centimeters 

 beyond it; (4) that after circus movements have been performed 

 in a given trial the animal often orients and moves directly toward 

 the source of light; and (5) that a change in illumination seems 

 to favor the performance of circus movements, since, out of 8 

 circus movements, 4 were made almost immediately after the 

 insect was placed in the beam and before it had reached the 

 edge of the beam, 3 were made at the edge of the beam, and only 

 1 was made elsewhere. 



On the second day in all of the first eight trials, except the 

 fifth, the butterfly assumed an angle of about 90 degrees with 

 the rays, and then traveled across the beam and into the shaded 

 region for a distance of from 1.5 to 9 cm. where orientation 

 occurred (fig. 3). In the fifth it continued on to the right in 



