Structure of the taste organs 282 Distribution in different orders of insects 282 Experimental proof 286
The ears or tympanal and chordotonal sense-organs of Orthoptera and other insects 288 Antennal auditory hairs 292 Special sense-organs in the wings and halteres 293
THE DIGESTIVE CANAL AND ITS APPENDAGES 297
The œsophagus 303 The crop or ingluvies 303 The “sucking stomach” or food-reservoir 305 The fore-stomach or proventriculus 306 The œsophageal valve 311 Proventricular valvule 313 The peritrophic membrane 313 The mid-intestine 314 Histology of the mid-intestine 316 The hind-intestine 316 Large intestine 316 The ileum 317 The gastro-ileal folds 317 The colon 317 The rectum 318 The vent (anus) 319 Histology of the digestive canal 320
The mechanism of secretion 326 Absorbent cells 328
THE GLANDULAR AND EXCRETORY APPENDAGES OF THE DIGESTIVE CANAL 331
_b._ The silk or spinning glands, and the spinning apparatus 339
The process of spinning 340 How the thread is drawn out 343 Appendages of the silk-gland (Filippi’s glands) 345
_d._ The excretory system (urinary or Malpighian tubes) 348
_h._ “Honey-dew” or wax-glands of Aphids 364
DEFENSIVE OR REPUGNATORIAL SCENT-GLANDS 368
Eversible coxal glands 369 Fœtid glands of Orthoptera 369 Anal glands of beetles 372 The blood as a repellent fluid 374 Eversible glands of caddis-worms and caterpillars 375 The osmeterium in Papilio larvæ 377 Dorsal and lateral eversible metameric sacs in other larvæ 377 Distribution of repugnatorial or alluring scent-glands in insects 382
The propulsatory apparatus 401 The supraspinal vessel 403 The aorta 404 The pericardial cells 405 Pulsatile organs of the legs 405
_b._ The pericardial fat-body or pericardial cells 420
Leucocytes or phagocytes in connection with the pericardial cells 421
The position and number of pairs of stigmata 439 The closing apparatus of the stigma 441
_c._ Morphology and homologies of the tracheal system 442
_e._ Origin of the tracheæ and of the “spiral thread” 447
_f._ The mechanism of respiration and the respiratory movements of insects 451
_h._ The closed or partly closed tracheal system 459
_i._ The rectal, tracheal gills, and rectal respiration of larval Odonata and other insects 463