REACTIONS TO LIGHT IN VANESSA ANTIOPA, WITH 

 SPECIAL REFERENCE TO CIRCUS MOVEMENTS 



WILLIAM L. DOLLEY, Jr. 



Professor of Biology, Randolph-Macon College 



From the Zoological Laboratory of The Johns Hopkins University 



Twenty-one figures 



CONTENTS 



Introduction 357 



Methods 367 



Behavior of normal specimens 370 



Behavior of specimens with but one functional eye 371 



A. Behavior in normal conditions of illumination 371 



B. Behavior in a beam of light 371 



1. Description of reactions — deflection, circus movements and orien- 



tation 371 



2. Relation between the degree of curvature in circus movements and 



the luminous intensity 382 



3. Relation between the angle of deflection and the luminous inten- 



sity 383 



a. Effect of beginning the trials in different intensities 383 



b. Effect of sudden changes of intensity on the angle of deflec- 



tion 386 



4. Reorientation after changing the direction of the beam of light. . 389 



C. Effect of the covering of the eye owing to cont'act 394 



D. Behavior in non-directive light 399 



E. Relation between the degree of curvature in circus movements and the 



luminous intensity of non-directive light 404 



1'' . Effect of illuminating only one eye 410 



1. Effect of illuminating the entire surface of one eye 410 



2. Effect of illuminating different areas of one eye 413 



General summary and conclusions 415 



Bibliography • 419 



INTRODUCTION 



One of the most thorough pieces of work, which have been 

 done on the reactions to hght in butterflies, is that reported by 

 Parker ('03) on the mourning-cloak butterfly, Vanessa antiopa. 



357 



