ANATOMY AND PHYSIOLOGY 



77 



Will fed wasps with sugar and then replaced it with powdered alum, 

 which the wasps unsuspectingly tried but soon rejected, cleaning the 

 tongue with the fore feet in a comical manner and manifesting other signs 

 of what we may call disgust. Forel offered ants honey mixed with mor- 

 phine or strychnine ; the ants began to feed but at once rejected the mix- 

 ture. In its range, however, the gustatory sense of insects differs often 

 from that of man. Thus Will found that Hymenoptera refused honey 

 with which a very little glycerine had been mixed (though Muscidae did 

 not object to the glycerine) and Forel found that ants ate unsuspectingly 

 a mixture of honey and phosphorus until some of them were killed by it. 

 Under the same circumstances, man would be able to detect the phos- 

 phorus but not the glycerine. 



Location of Gustatory Organs. As would be expected, the end- 

 organs of taste are situated near the mouth, commonly on the hypo- 



tb 



sc 



g 



FIG. 126. Section through tongue of wasp, Vespa i'ul- 

 garis. c, cuticula; g, gland cell; /?, hypodermis; n, nerve; 

 ob, gustatory bristle; pli, protecting hair; sc, sensory cell; 

 tb, tactile bristle. After WILL. 



FIG. 127. Tongue of honey 

 bee, Apis well if era. ^protect- 

 ing bristles; s, terminal spoon; 

 /, taste setae. After WILL. 



pharynx (Fig. 126), epipharynx and maxillary palpi. On the tongue of 

 the honey bee the taste organs appear externally as short setae (Fig. 127) 

 and on the maxillae of a wasp as pits, each with a cone, or peg, projecting 

 from its base (Figs. 128, 129). Similar taste pits and pegs have been 

 found by Packard on the epipharynx in most of the mandibulate orders of 

 insects. 



Histology. The end-organs of taste arise from special hypodermis 

 cells, as minute setae or, more commonly, pegs, each seated in a pit, or 

 cup, and connected with a nerve fiber (Figs. 129, 130). In some cases, 

 however, it is difficult to decide whether a given organ is gustatory or 

 olfactory, owing to the similarity between these two kinds of structures. 



