OLFACTORY SENSE OF THE HONEY BEE 281 



To ascertain the true responses of bees to the odors of the 

 preceding substances, the chosen insects were carefully observed 

 each day as long as they lived. A bee was tested only when it 

 became perfectly quiet, without even the antennae being moved 

 in the least, and when it was not watching another bee or any 

 other object, and was not eating. The stopper was quickly re- 

 moved and the vial was then gently and slowly placed under 

 the observation case directly beneath and within ^ inch of the 

 individual being tested. Occasionally the vial was placed a few 

 inches in front of the specimen, to test its ability of smelling for 

 a short distance. Whenever all of these precautions are taken, 

 a normal bee responds to any one of these odors without failure. 

 As a control, an empty and odorless vial was now and then 

 placed under the bees in the same manner. If by chance a bee 

 moves while the control test is being made, its behavior is quite 

 different from that observed when odors are used. Only the 

 first responses have been recorded, and in all cases where there 

 was the least doubt as to whether the bee moved for any reason 

 other than the olfactory stimulus, such movements were never 

 recorded. The reaction time was counted in seconds. With an 

 ordinary watch the minimum time which can be definitely re- 

 corded is 2 seconds, although many individuals respond to some 

 of the odors much more promptly. Owing to this source of 

 error the average recorded time is probably double what it should 

 be in the cases where the response was prompt. An intermission 

 of 15 minutes elapsed between any two tests in the same obser- 

 vation case and generally several times this period elapsed be- 

 fore the ssLTtie bee was again tested with the same or with a differ- 

 ent odor. Some individuals were tested five times with the same 

 odor, although most of them were not so tested more than twice. 

 In all, 509 specimens have been carefully observed, but on ac- 

 count of the extreme restlessness of some of the bees it has been 

 possible to obtain records for only 263. 



In the following paragraphs are given the responses of the 

 three castes of bees to the odors of the ten different substances 

 and the average reaction times in seconds. . In recording the 

 responses the term "vibrate" is used to describe the rapid move- 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 16, NO. 3 



