PHOTIC REACTIONS OF HONEY-BEE 347 



tain flies. Thus Radl ('03, p. 62) says, ''Die Calliphora vomi- 

 toria bewegt sich fast ebenso gerade mit einem geschwarzten Auge, 

 wie wenn sie aus beiden sieht, und es ist mir nicht leicht, diese 

 Erscheinung zu erkljiren." Carpenter ('08, p. 486) states that 

 Drosophila with one eye blackened "crept in a fairly direct path 

 toward the light, although a tendency to deviate toward the 

 side of the normal eye regularly occurred." It is possible, I 

 believe, to interpret these cases as merely more extreme instances 

 of modifiability, in which regulation occurs very rapidly instead 

 of after a more or less prolonged experience. 



That modifiability is operative, at least in the case of Droso- 

 phila, is evidenced by the following statement of Carpenter (p. 

 486) . ''The tendency to diverge from the direct path toward the 

 side of the uncovered eye was overcome by a series of short, quick 

 turns in the opposite direction, which kept them headed toward 

 the light." Further evidence in the case is afforded by the be- 

 havior of one fly which, according to Carpenter, persisted in per- 

 forming circus movements. This fly, however, (p. 486) "had 

 long been active, and showed signs of fatigue." As will be shown 

 later, very similar phenomena were observed in the honey-bee. 

 In conditions, such as that of weakness, induced by long 

 experiment, the bee frequently circled much more toward the 

 functional eye than it had formerly done. It seems probable 

 that in such states the animal approximates more nearly to a 

 simple, reflex behavior. Factors effective in modifying behavior 

 in the vigorous animal have ceased to be operative. 



If these interpretations be correct, the conspicuous absence of 

 circus movements in Drosophila is only an extreme case of modi- 

 fiability, and offers no real objection to the general conclusion to 

 be drawn from these reactions. However, further work is neces- 

 sary upon both Drosophila and Calliphora before they may be 

 disposed of with certainty. 



Responses of still another kind have seemed perhaps the most 

 formidable obstacle to any general conclusion as to the occur- 

 rence of circus movements. Thus Hadley ('08, p. 197) has shown 

 that whereas the 'progressive orientation' of the lobster larva 

 after the blinding of one eye is positive, the larva performs circus 



