400 DWIGHT E. MINNICH 



uli which were quite unavoidable. An animal was accidentally 

 pressed slightly in changing it from one cage to another, or, fail- 

 ing to react to photic stimulation, the cage had to be shaken. 

 Again, in transferring a bee from the light to which it was sub- 

 jected for activation to the center of the non-directive light cham- 

 ber, it was subjected to increases and decreases of light intensity. 

 All of these details and endless others, collectively and individu- 

 ally, were undoubtedly responsible for many of the sudden 

 variations of behavior which occurred. 



b. Internal. The chief causes of irregular variations, however, 

 are internal. When under constant external conditions, a bee 

 varies the direction of its turning several times in the course of a 

 single trial, the behavior must be attributed to changes within the 

 animal itself, the physiological states of Jennings ('06). Gener- 

 ally speaking, the analysis of these changing physiological states 

 is difficult or impossible. In several instances, however, I was 

 able to make a fairly certain diagnosis. I may cite several 

 examples. 



Bee no. 147 was subjected to the usual quantitative experi- 

 ment in non-directive light. From the beginning this animal 

 exhibited a rapid, uneasy locomotion. Its entire behavior may 

 best be described by the word 'excitable.' In the course of the 

 first day after the eye was blackened, five pairs of determinations 

 were made. In 24 mc. light, the animal circled chiefly toward 

 the covered eye, while in 957 mc, its behavior varied from one 

 set of records to another. 



On the following morning, the first pair of determinations was 

 begun at 9:49. The bee circled markedly toward the covered 

 eye in both intensities of light. At 12:14, a second pair of 

 determinations was begun. In making the first trial, the bee 

 rushed about its cage for some minutes before finally creeping up 

 into the non-directive light chamber. When it did appear, it 

 seemed greatly excited and crept very rapidly. As the series of 

 records progressed, the animal circled more and more pronouncedly 

 toward the functional eye, the locomotion grew more rapid, and 

 a continuous buzzing began. The performance of small circles 

 toward the functional eye in 24 mc. light was surprising, for in 



