OLFACTORY SENSE OF THE HONEY BEE 297 



crease of time can certainly be attributed to the abnormal con- 

 dition of the bees, and these results indicate that the olfactory 

 organs are located elsewhere. At most it can be claimed only 

 that the antennae may assist in the receiving of odor stimuli. 



MAXILLAE AND LABIAL PALPI 



Various observers claim that the palpi of insects are the seat 

 of the olfactory organs. In the bee the maxillary palpi are al- 

 most wanting, but the maxillae and labial palpi possess pore-like 

 sense organs. These appendages were cut off at the base. When 

 introduced into observation cases, bees so treated appeared quite 

 normal in all other respects and when strange bees were put 

 among them they lost no time in attacking the strangers. Never- 

 theless, they certainly were not completely normal, for they lived 

 only from 3 hours to 4 days, with 24 hours as an average. When 

 tested with odors, they gave responses similar to those of unin- 

 jured bees. The reaction time was as follows: Oil of pepper- 

 mint 2.2 seconds, oil of thyme 3.7 seconds, oil of wintergreen 

 4 seconds, honey and comb 4.4 seconds, pollen 5.8 seconds, and 

 leaves and stems of pennyroyal 3.9 seconds. This gives a gen- 

 eral average of 4 seconds, whereas for the same odors with un- 

 mutilated bees the general average was 3.4 seconds. 



PROBOSCIS 



Several writers have described sense organs on the proboscis 

 of insects. To determine whether these have an olfactory use, 

 the proboscides of 36 workers were cut off close to the base. 

 These bees seemed quite normal in most respects and many of 

 them even tried to eat candy, but of course they could not accom- 

 plish much without this appendage. They lived only 7 hours 

 on an average. The average reaction time to oil of peppermint 

 was 2.6 seconds, to oil of thyme 3 seconds, and to oil of winter- 

 green 3.2 seconds. This gives a general average of 2.9 seconds, 

 while for the same odors with unmutilated bees the average 

 was 2.6 seconds. Twenty-two workers were tested. We can 

 probably attribute this difference of 0.3 seconds to the abnor- 

 mality of the mutilated bees. 



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



