CONTRIBUTIONS FKOM THE ZOOLOGICAL LABORATORY OF THE MUSEUM OF COMPARATIVE ZOOLOQT AT 



HARVARD COLLEGE. NO. 252. 



A QUANTITATIVE DETERMINATION OF THE ORIENT- 

 ING REACTION OF THE BLOWFLY LARVA 

 (CALLIPHORA ERYTHROCEPHALA MEIGEN) 



BRADLEY M. PATTEN 



TWENTY-FOUR FIGURES 



CONTENTS 



Statement of the problem 213 



Literature 214 



Apparatus ' 220 



Material and Methods. 223 



1. Cultures " 223 



2. Variability of response 224 



3. Standard test 225 



4. Plan of experiments 228 



5. Making the trails 229 



6. Elimination of asymmetry 230 



7. Measurement and tabulation 232 



Tabular and graphic statement of results 239 



Discussion .' 244 



1. The scale of reactiveness 244 



a. Determination 244 



b. Application 248 



2. Theories of orientation 251 



a. The relation of phototaxis to photokinesis 251 



b. Orientation in the blowfly larva 252 



c. Analysis of factors involved in phototaxis 272 



Summary and conclusions 276 



Bibliography 279 



STATEMENT OF THE PROBLEM 



In the work done thus far in animal behavior, no successful 

 attempt has been made to apply any form of precise measure- 

 ment to movements produced by light of known differences in 

 intensity. The experiments on the blowfly larva described in 

 this paper were devised for the purpose of making exact quan- 



213 



