THE SENSES OF INSECTS McINDOO. 473 



dissolved in the liquids of the mouth may give rise to actual tastes. 

 The sense of taste is brought about by substances either in solution 

 when introduced into the mouth or dissolved by the liquids in the 

 mouth. Parker and Stabler, after experimenting upon themselves, 

 and Professor Parker upon other vertebrates, say: 



"We therefore definitely abandon the idea that taste and smell differ on the 

 basis of the physical condition of the stimulus, a state of solution for taste, 

 a gaseous or vaporous condition for smell, and maintain that both senses are 

 stimulated by solutions, though in smell, at least for air-inhabiting verte- 

 brates, the solvent is of a very special kind * * *. In air-inhabiting ver- 

 tebrates the olfactory solvent is a slimy fluid of organic origin and not easily 

 imitated. 



From the preceding definitions it is evident that the senses of smell 

 and taste in vertebrates can not be sharply separated, and the follow- 

 ing discussion will show that these two senses in the honey bee can 

 not be separated at all. In the honey bee it will be shown that the 

 sense of taste is only one phase of the olfactory sense. We have 

 not the slightest conception as to how odor and taste stimuli in any 

 animal act upon nerve endings to produce the various sensations of 

 smell and taste, and as shown in the following pages, when bees 

 are fed foods which contain undesirable substances emitting extremely 

 weak odors the}?- refuse to eat the foods after "tasting" them. In 

 view of the two preceding facts we may call this perception an 

 olfactory-gustatory sense, although the writer will endeavor to show 

 that the gustatory sense plays no part in these responses. 



Since it is impossible to eliminate the olfactory sense while deter- 

 mining whether bees have a true gustatory sense, and as the various 

 sense organs on the mouth parts can not be mutilated without causing 

 considerable abnormality in the behavior of the bees while eating, 

 it was decided to ascertain if bees have likes and dislikes in regard 

 to foods and to make a careful study of the structure of all the 

 sense organs on the mouth appendages in order to be able to judge 

 whether or not bees have a true sense of taste. 



The preliminary experiments in feeding bees foods containing 

 various substances suggested five classes of foods to be used in other 

 experiments. Foods containing strong repellents were employed to 

 determine the importance of the olfactory sense in causing bees to 

 avoid such substances, and foods containing sweet, bitter, sour, and 

 salty substances were used to ascertain if bees show preferences 

 between foods having the four attributes of human taste. Pure cane- 

 sugar candy (powdered sugar mixed with honey) and honey were 

 used as standard or control foods and the five classes of foods em- 

 ployed are as follows: (1) Repellents — carbolic acid, oil of pepper- 

 mint, whiskey, formic acid, xylene, formaldehyde, kerosene, and lime- 

 sulphur, each mixed with candy or honey; (2) sweet foods — candies 



