PHOTIC REACTIONS OF HONEY-BEE 401 



all previous record sets for this intensity, the animal had shown a 

 more or less pronounced tendency to circle toward the covered 

 eye. In the course of the fourth trial in 957 mc. light, the bee 

 had reached a state of intense excitation. Its turning became so 

 rapid, and the consequent circles so small, that at length the 

 animal tumbled over on its back. Defaecation occurred. Mean- 

 while it continued buzzing loudly, and, though lying on its back, 

 managed to whirl round and round toward the functional eye. 



After the trial just described, the animal was allowed to rest for 

 two hours. At 2:44 and 4:10, respectively, two more pairs of 

 determinations were made. The bee continued to circle markedly 

 toward the functional eye in 957 mc. light, and more or less toward 

 the functional eye in 24 mc. light. The 'excitement' which had 

 characterized the previous trials, however, was absent, and the 

 animal manifested signs of weakness and exhaustion. 



In the behavior of this animal there was a sudden — even vio- 

 lent — increase of phototropism. This was probably due to an 

 unusual intensification of activity. I have repeatedly observed 

 the close correlation between these two features of behavior in 

 bees. As a rule, the greater the activity, the more pronounced 

 is the manifestation of phototropism. The increase of activity 

 in this animal was produced by a state of metabolism, entailed 

 by a collection of faeces in the intestine. That such a condition 

 may affect the activity of bees to a marked degree is evidenced by 

 the following statement made by Phillips and Demuth ('14, p. 

 12) in connection with a study of certain hive conditions in win- 

 ter. "It therefore appears that the accumulation of feces (in 

 the intestine) acts as an irritant, causing the bees to become more 

 active and consequently to maintain a higher temperature." 



In several other animals defaecation occurred in the course of 

 a trial without being preceded by any conspicuous change of 

 behavior. Neither the amount voided nor the force of expulsion, 

 however, gave any evidence of long accumulation or intestinal 

 irritation in these cases. It seems reasonably certain, therefore, 

 that the sudden increase of phototropism exhibited by bee no. 

 147 was due to the accumulation of faeces in the intestine. 



