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WILLIAM L. DOLLEY, JR. 



these were tested on several successive days. In nearly all cases 

 the animals were forced to record their reactions on carbon 

 paper, as previously described. In all tests the butterflies were 

 placed in the beam so that they faced the light directly. The 

 results obtained varied considerably in different individuals and 

 also in the same individual under different conditions. In some 

 respects, however, there was but little variation. 



Nearly all of the butterflies tested turned toward the functional 

 eye immediately after they were exposed, regardless of the 

 luminous intensity or the axial position with reference to the 



Fig. 1 Reproduction of various trails made by different specimens of Vanessa 

 with the left eye blackened when exposed in a beam from a Nernst glower. The 

 diverging straight lines represent the limits of the horizontal beam. The arrows 

 indicate the direction of motion. Their trails show that there is great variation 

 in the reactions of different individuals under the same conditions. 



direction of the rays of light. Some of them continued to turn 

 in this direction making repeated circus movements^ (fig. 1, a 

 and b) until they became fatigued and stopped, or until they 

 reached the edge of the beam, where many turned sharply toward 

 the glower and traveled along the edge of the beam toward 

 the source of light, as is shown in figure 1, c. A few, however, 

 did not turn toward the light when they reached the edge of the 

 beam, but passed into the shaded region, continuing to make 

 circus movements (fig. 1, e). Others did not make circus move- 

 ments, but turned until the longitudinal axis made a certain 



* In the present paper the term 'circus movements' with no further explanation 

 means continuous movement toward the functional eye. 



