354 DWIGHT E. MINNICH 



slide operated by a handle (fig. 2, h), it was possible, after in- 

 serting the cage, to open or close the light chamber at will. The 

 difficulties involved in direct manipulation of bees were thus 

 entirely avoided. An individual to be tested in non-directive 

 light was merely allowed to creep into the cage, which was then 

 inserted into the opening in the table top. The slide was then 

 pushed aside and the bee allowed to creep up on to the floor of the 

 apparatus. As soon as the bee had entered the light chamber, 

 the slide was pushed back, closing the entrance and leaving the 

 floor of the apparatus complete. 



The ideal apparatus for studying the effects of continuous pho- 

 tic stimulation of a constant intensity would be one so constructed 

 that all the ommatidia of a compound eye would receive equal 

 illumination, irrespective of the direction of locomotion. Such 

 an apparatus is virtually a physical impossibility. However, 

 the apparatus just described is perhaps somewhat of an approxi- 

 mation to it, even if it does not afford an absolutely uniform light 

 intensity over the floor of the light chamber. As table 1 shows, 

 the illumination is more intense toward the center. Some fluc- 

 tuation will, therefore, occur in the stimulation of the various 

 ommatidia as the animal moves. However, in any position 

 whatever on the floor of such a light chamber, all the ommatidia 

 are receiving some stimulation. Moreover, the amount of stimu- 

 lation received by those areas of the eye which are minimally 

 affected does not differ vastly from that received by areas of 

 maximal stimulation. 



b. Records. The method of recording behavior in non-directive 

 light is illustrated in figures 3 and 4. The animal to be tested 

 was transferred to the light chamber, and its course of creeping, 

 observed through the 'peep hole' in the curtain, was traced as care- 

 fully as possible on a record sheet. The record bore a plan simi- 

 lar to that on the floor of the light chamber, drawn on a scale of 

 1 to 6. The duration of each trial was ascertained by counting 

 the rings of an electric bell, attached to an electric clock regulated 

 to seconds. How long the trial should last was determined by 

 an interval previously decided upon or by the animal encountering 

 the side wall of the chamber and creeping up. On completion of 



