INDEX. 



767 



in 



Optic cap, 452, 472 



development of, 473 

 Optic constants of compound eye, 581 

 Optic cup, 326 

 Optic discs in larva, 80 



in nymph, 327 

 Optic ganglion, 451, 469 



in Astacus, 446 



cell-groups in, 471 



development of, 483 



evolution of, in pronymph, 492 



structure of, 469 

 Optic nerve, 469, 470 



external chiasma of, 537 



supposed terminations of, 



great rods, 537 

 Optic peduncle, 452, 469 

 Optic stalk, 80, Si, 327, 545 



development of, 327 

 Optogenic cells, 547 

 Oral lobes, 395 

 Oral sucker of proboscis, 135 



function of, 397 



inflation of, 397 



internal structure of, 393 



skeleton of, 135 

 Orthoptera, auditory organs of, 595 



brain of, 462 



chordotonal organs of, 595 



labium of, 14 



mesosternum of, 168 



metameres of, 15 



protandry in, 723 



sexual act in, 664 



tympana of, 599 



vitellus of, 701 

 Orthoraphic Diptera, 29 

 Oscornutum, 183 

 Osmium peroxide, action of, on nerve 



centres, 66, 468, 473 

 Osten-Sacken on chaetotaxy, 10 



on metapleuron, 174 



on sensory bristles, 499 



on sutures of thorax, 166 

 Ostia of dorsal vessel, 641 

 Ouljanin on development of external 



sexual organs, 731 

 Ova, origin of, 720. See Ovum, Germ, 



Vitellus, and Egg 

 Ovarian follicles, 699 

 Ovary, 666 



development of, 691, 698 



epithelial tubes in, 700 



neck of, 689 



Ovary, peritoneal coat of, 669 



structure of, 666 

 Oviduct, 666, 671 



development of, 705 



termination of, in Hymenoptera, 



736 



Ovipositor, 733, 745 

 Ovum, 12 



changes in, before impregnation, 



714 



development of, 701 

 early changes in formation of 



blastoderm, 230 

 general observations on, 707 

 holoblastic, 236, 707 

 meroblastic, 708 

 meroistic, 701, 709 

 nature of, 707 

 panoistic, 701, 708 

 Owsjannikow on nerve fibres, 437 

 Oxygen, relation of, to work done, 384 



PACHYTYLUS, M tiller's organ in, 600 

 Packard on development of male 



organ, 731 



Pain doubtful in Insects, 497 

 Palisade cells of Carriere, 535, 536 

 Palmen on morphology of tracheae, 



356 



on paired genital ducts, 660, 735 



on tracheal gills, 180 

 Palpi. See Labial and Maxillary palpi 

 Palpiger, 133 

 Palpigerous scales, 135 

 Pancreatic glands of Invertebrates, 



416 



Panoistic ova, 701, 708 

 Parablast, 234 



origin of, 333 

 Parablastic tissues, 270 

 Paracephala, 114 



of imago, 121 



of nymph, 116 

 Paraderm, 296 



contraction of the, 305 



formation of the, 299 



relation of, to discs, 303 

 Parafrontals, 121 

 Paragastric tracheae, 225 

 Paraglossae, 132, 147 

 Paragonia, 662 



development of, 691, 692 



functions of, 663 

 Paranucleus, 269 



50 



