AUTHOR S ABSTRACT OF THIS PAPER ISSUED 

 BT THE BIBLIOGRAPHIC SERVICE, OCTOBER 8 



REACTIONS OF LAND ISOPODS TO LIGHT 



CHARLES HARLAN ABBOTT 

 Biological Laboratory, Brown University 



CONTENTS 



I. Introduction 194 



IL Historical 195 



III. Material 196 



IV. Normal behavior 197 



A. Reactions to light 197 



1. Photokinesis 197 



2. Phototaxis 197 



3. Vision. .-. 198 



B. Relation of contact and vision 198 



V. Experiments with directive light 199 



A. Apparatus 199 



B. Normal reactions 205 



1. Positive and negative responses 206 



2. Orientation 208 



3. Angle of negativeness 211 



4. Conclusions 214 



C. Modifiability of the light reactions 215 



1. Reaction to different intensities 216 



2. Effect of repeated stimulation. 220 



3. Comparison of reactions following exposure to light and to 



dark 223 



4. Comparison of reactions of individuals from dry and moist 



habitats 225 



5. Reaction in water 226 



6. Comparison of phototaxis in Oniscus and Porcellio 228 



7. Conclusions 230 



VI. Discussion • 231 



A. Ecological analysis 231 



1. Habitat 232 



2. Structural and physiological adaptations 232 



a. Respiration 232 



b. Food 233 



c. Care of young 233 



d. Behavior 233 



193 



