318 N. E. McINDOO 



resemblance to these olfactory pores. Janet ('11a) speaks of a 

 chordotonal organ at the base of the antenna in the bee, but it 

 has no resemblance to the olfactory pores. Hicks ('60) also 

 found some pores on the proboscis and palpi of the honey bee 

 and of other insects. Breithaupt ('86) also describes some pores 

 found on the base of the bee's proboscis. The drawings of the 

 last two authors are not clear, so far as the anatomy of the pores 

 is concerned. These same pores are found not only at the base 

 of the proboscis but elsewhere on this appendage and also on 

 the labial palpi and maxillae. Their superficial appearance is 

 similar to the olfactory pores. Briant ('84) describes sense hairs 

 on the proboscis and maxillae of the honey bee; these hairs, 

 however, have nothing in common with the olfactory pores. 

 Packard ('89) and Nagel ('97) find hairlike sense organs in the 

 buccal cavity of various insects, but their structure does not 

 resemble that of the olfactory pores. In all probability none of 

 these organs on the head appendages is homologous in structure 

 and function to the olfactory pores, except those on the mouth 

 parts, but a more critical study of them would be required be- 

 fore anything definite could be stated concerning them. While 

 it would not be surprising to find the olfactory pores in places 

 other than those already named, nevertheless it is believed that 

 nearly all, if not all, have been found. 



STRUCTURE 



External structure 



When examined under a low-power lens the olfactory pores may 

 be easily mistaken for hair sockets from which the hairs have 

 been removed. When more carefully observed, even under a 

 low-power lens, a striking difference in external form is seen. The 

 five groups on the wings are quickly detected, but those on the 

 legs and sting are not so readily found. If the preparation is 

 dark, the pores appear as small bright spots, when a strong trans- 

 mitted light is used. Looking at these areas under a high-power 

 lens each one appears to have a dark boundary, or pore wall 

 (fig. 5, PorW). Near the center of this boundary is a trans- 



