THE SENSES OF INSECTS McINDOO. 475 



tory pores, marked Poi\ in figure 9. Neither kind of these sense 

 organs is suitable as taste organs. 



The present writer, and the few other authors who have fed in- 

 sects foods containing undesirable substances, have observed that the 

 insects sooner or later refuse such foods after eating more or less of 

 them. Judging from this behavior, the other authors have con- 

 cluded that insects can taste, regardless of knowing whether or not 

 they have sense organs anatomically adapted for receiving gustatory 

 stimuli, and without considering the role played by the olfactory 

 sense in these responses. As Parker has already said for vertebrates, 

 and as we well know for ourselves, it is almost impossible to de- 

 termine whether we taste or smell certain substances when we eat 

 them. To us sometimes a food, before being eaten, emits only a faint 

 odor or no odor at all ; but when we eat it, we perceive a pronounced 

 odor. In such a case the odorous particles are not given off until the 

 food is taken into the mouth and mixed with saliva. The same prin- 

 ciple is certainly applicable when bees eat candies which contain 

 undesirable substances emitting extremely weak odors. As quickly 

 as the saliva has dissolved the candy and has had time to effect a 

 chemical or physical change, the odorous particles are given off, and 

 since the olfactory pores on the mouth parts are nearest the food, 

 they are the first ones to receive the odorous particles. For this 

 reason the so-called gustatory sense in insects is only a phase of 

 the olfactory sense. 



That we can not smell certain substances is no proof that insects 

 can not smell them, for the many experiments performed by the 

 present writer cause him to believe that the olfactory sense in the 

 honeybee is much more highly developed than ours. 



It is reasonable to think that many foods and chemicals emit odors, 

 although we may not be able to perceive all of them; but judging 

 from the experiments cited, it is not impossible for bees to discrimi- 

 nate between them better than we can. If they are not able to do 

 this without eating them, only a few " tastes " are necessary to demon- 

 strate their preferences. In a few instances the present writer was 

 not able to discriminate differences between candies containing cer- 

 tain chemicals by using both senses of smell and taste, but the bees 

 were able to distinguish marked differences. It therefore seems evi- 

 dent that this faculty in the honeybee is more highly developed than 

 in man. 



In all probabilitj* bees have no other means of chemically discrimi- 

 nating between foods than by smelling them, because no sense organs 

 were found connected with the alimentary tract between the pharynx 

 and the honey stomach, and because the innervated hairs described 

 are not anatomically adapted for this purpose. The walls of the ali- 



