194 CHARLES HARLAN ABBOTT 



3. Reactions of land isopods 234 



a. Reactions to humidity and evaporation 234 



h. Reactions to contact 235 



c. Reactions to light 235 



B. The problem of orientation 238 



L Direct orientation versus method of trial 239 



2. Constant intensity versus change of intensity 239 



3. Conclusions 243 



VII. Summary 243 



VIII. Bibliography 245 



I. INTRODUCTION 



Land isopods, commonly called sowbugs, have always been of 

 interest as the only Crustacea which are truly terrestrial. How- 

 ever, most previous studies of the adaptation of this group of 

 animals to a land environment have been devoted only to the 

 structure and function of the respiratory organs. The behavior 

 has been almost entirely neglected. Behavior studies, always of 

 interest to comparative psychologists, have been made increas- 

 ingly important by the recent development of animal ecology 

 into an experimental science, in which behavior is used as a test 

 of the influence of environment. This use of behavior investi- 

 gations is emphasized in the general ecological works of Adams 

 ('13) and Shelf ord ('13), and has been applied by Banta ('10) 

 and Allee ('12, '14) to the study of fresh-water isopods. 



The present study of land isopods has therefore been under- 

 taken in order to learn if their behavior is of ecological im- 

 portance. The plan has been, 1) to study the reactions to in- 

 dividual factors of the environment, and 2) to find out if these 

 reactions assist in fitting the animals in question to occupy their 

 present habitat. 



This paper reports a study of the behavior of land isopods 

 with respect to one of the most important environmental factors, 

 namely, light. Although the results are considered also from the 

 standpoint of the problems which particularly interest all stu- 

 dents of animal behavior, the ecological viewpoint has been the 

 guiding principle throughout. 



The experiments were carried on at the Biological Laboratory, 

 Brown University. I wish to thank the authorities of the uni- 



