NO. 14 SENSE ORGANS ON MOUTH-PARTS OF BEE— MdNDOO 21 



gations indicate that no substitute can be had which will be liked 

 by bees as well as the best pure honey. 



The fact that bees must first eat more or less of the foods before 

 being able to discriminate differences between them, unless they con- 

 tain repellents, indicates that bees have a true gustatory sense, pro- 

 viding this discrimination is not accomplished by means of the 

 olfactory sense. Since this point cannot be determined experi- 

 mentally, our only criterion is to make a thorough study of all the 

 sense organs on and near the mouth-parts. This part of the work is 

 given in the following pages. 



MORPHOLOGY OF THE SENSE ORGANS ON THE MOUTH-PARTS 

 OF THE HONEY BEE 



In the preceding pages it is stated that bees show preferences 

 between foods. In order that they may show preferences between 

 the foods emitting weak odors, it is first necessary for them to eat 

 a little of the foods. This fact indicates that bees may have a true 

 sense of taste. If the mouth-parts possess sense organs which are 

 anatomically fitted for receiving gustatory stimuli, we are safe in 

 saying that bees can taste. In order to find such organs, if possible, 

 it was necessary to make a special study of all the sense organs on and 

 near the mouth-parts. In order to distinguish the sense organs from 

 other structures on the mouth-parts, the internal anatomy of all the 

 structures on the integument was first studied. This was accom- 

 plished by making many transverse and longitudinal sections through 

 all parts of the mouth-appendages and even through the entire head. 

 Only two general types of sense organs were found; 'viz.: inner- 

 vated hairs and innervated pores. 



Hairs on the honey bee are of two kinds— branched or barbed hairs 

 and unbranched ones. As far as known the branched ones are never 

 innervated and are never found on the mouth-appendages, but on 

 the head near the mouth-parts and elsewhere. The unbranched 

 hairs not only occur on the mouth-appendages but also on the other 

 parts of the integument, although most abundantly on the mouth- 

 parts and compound eyes. They may or may not be innervated. 



All true hairs, whether branched or unbranched, arise from hair 

 sockets (fig. 2 Q, HrSk) whose cavities (SkCav) communicate with 

 the lumens (L) of the appendages and with the cavities (HrCav) 

 of the hairs. The long hairlike structures (fig. 3 A. Hr 1 ) on the 

 tongue or glossa may be called pseudo-hairs, because they are merely 



