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WILLIAM BKODBECK HERMS 



face, otherw-se they roll over and over in attempting to creep on 

 a smooth, dry surface. The plate smeared with fish juices pre- 

 vented the unequal distribution of odors which might complicate 

 the movements of the feeding larvae. The migrated larvae on 

 the other hand were allowed to creep on glass which was fre- 

 quently sponged with tap water to provide a moist surface on 

 which the larvae could crawl and to obliterate previous trails. 



The data for table 3 are based on a series of experiments on the 

 ten individuals throughout their life history, except when in a 

 few cases new larvae were substituted for those accidentally 

 lost. Each was isolated after hatching b}^ being placed in a small 

 cardboard box with its own piece of fish. The results of this series 

 of experiments are tabulated as follows : 



TABLE 3 

 Summary of reactions of Lucilia caesar {Lot no. 10) at different ages to directive 



* See table 4 for same date. 



t This aberrant reaction was on the part of an individual whose wings did not 

 spread ; it was consequently forced to creep. All other adults first perched on the 

 edge of the vial in which they were retained and then flew toward the light. 



