xii TEXT-BOOK OF ENTOMOLOGY 



PAGE 



The pigment .......... 253 



The basilar membrane . 253 



The optic tract . . 253 



Origin of the facetted eye .... . 255 



Mode of vision by single eyes or ocelli ..... 255 



Mode of vision by facetted eyes 256 



The principal use of the facetted eye to perceive the move- 

 ments of animals ........ 259 



How far can insects see ? . 260 



Relation of sight to the color of eyes 260 



The color sense of insects .... . 200 



b. The organs of smell ....... 264 



Historical sketch of our knowledge of the organs of smell . 204 



Physiological experiments ..... . 268 



Relation of insects to smelling substances before and after the 



loss of their antennae 260 



Experiments on the use of the antennae in seeking for food . 270 

 Experiments testing the influence of the antennae of the males 



in seeking the females .... . 270 

 Structure of the organs of smell in insects . . .271 



c. The organs of taste ....... .281 



Structure of the taste organs . 



Distribution in different orders of insects 282 



Experimental proof ......... 286 



d. The organs of hearing ....... . 287 



The ears or tympanal and chordotonal sense-organs of Ortliop- 



tera and other insects ....... 288 



Antennal auditory hairs ........ 202 



Special sense-organs in the wings and halteres .... 293 



e. The sounds of insects 293 



THE DIGESTIVE CANAL AND ITS APPENDAGES ...... 297 



rt. The digestive canal ........ 30-_> 



The oesophagus .......... 303 



The crop or ingluvies ..... . 303 



The " sucking stomach " or food-reservoir . . . 305 



The fore-stomach or proventriculus ...... 306 



The cesophageal valve ...... .311 



Proventricular valvule ...... 31:5 



The peritrophic membrane . . . . . . .31:'. 



The mill-intestine ....... 314 



Histology of the mid-intestine ..... . 310 



The hind-intestine .31(5 



Large intestine ........ 316 



The ileum 317 



The gastro-ileal folds . . . . . . .317 



The colon ......... 317 



The rectum 318 



