xiv TEXT-BOOK OF ENTOMOLOGY 



PACK 



c. The oenocytes 423 



d. The phosphorescent organs 424 



Physiology of the phosphorescence 426 



THE RESPIRATORY SYSTEM ....... 439 



a. The tracheae ........ 431 



Distribution of the tracheae ..... 432 



b. The spiracles or stigmata ......' 437 



The position and number of pairs of stigmata .... 4:',<) 



The closing apparatus of the stigma 441 



c. Morphology and homologies of the tracheal system . . . 442 



d. The spiral threads or taenidia ....... 444 



e. Origin of the tracheae and of the " spiral thread ". . . .447 



Internal, hair-like bodies ....... 451 



/. The mechanism of respiration and the respiratory movements of 



insects 451 



g. The air-sacs 456 



The use of the air-sacs 457 



h. The closed or partly closed tracheal system 459 



i. The rectal, tracheal gills, and rectal respiration of larval Odonata 



and other insects ........ 463 



j. Tracheal gills of the larvae of insects 466 



Blood-gills 475 



k. Tracheal gills of adult insects . 476 



THE ORGANS OF REPRODUCTION 486 



a. The male organs of reproduction 494 



The testes 495 



The seminal ducts 496 



The ejaculatory duct . . . . . . . 497 



The accessory glands 497 



The spermatozoa . . . . . . . . 497 



Formation of the spermatozoon 498 



b. The female organs of reproduction 500 



The ovaries and the ovarian tubes ...... 600 



Origin of incipient eggs in the germ of the testes . . . 504 



The bursa copulatrix ......... 506 



The spermatheca 606 



The colleterial glands ........ 606 



The vagina or uterus 607 



Signs of copulation in insects 607 



PART II. EMBRYOLOGY OF INSECTS 



a. The egg 5ir, 



Mode of deposition 518 



Vitality of eggs 520 



