The number of moults in insects of different orders 615 Reproduction of lost limbs 619 Formation of the cocoon 619 Sanitary conditions observed by the honey-bee larva, and admission of air within the cocoon 623
_a._ The pupa considered in reference to its adaptation to its surroundings and its relation to phylogeny 631
_b._ Mode of escape of the pupa from its cocoon 632
Mode of formation of the cremaster and suspension of the chrysalis in butterflies 637
FORMATION OF THE PUPA AND IMAGO IN THE HOLOMETABOLOUS INSECTS (THE DIPTERA EXCEPTED) 640
The changes in the head and mouth-parts 646 The change in the internal organs 647 The wings 654 Development of the feet and of the cephalic appendages 654 Embryonic cells and the phagocytes 655 Formation of the femur and of the tibia; transformation of the tarsus 656 The antennæ 657 Maxillæ and labial palpi 658 Process of pupation 660
Ocular or oculo-cephalic buds 665 The antennal buds 665 The buds of the buccal appendages 665 The buds of the ovipositor 665
DEVELOPMENT OF THE IMAGO IN THE DIPTERA 666
_a._ Development of the outer body-form 668
Formation of the imago in Corethra 668 Formation of the imago in Culex 670 Formation of the imago in Chironomus 671 Formation of the imago in Muscidæ 673
_b._ Development of the internal organs of the imago 678
The hypodermis 678 The muscles 680 The digestive canal 681 The tracheal system 683 The nervous system 684 The fat-body 685 Definitive fate of the leucocytes 685 The post-embryonic changes and imaginal buds in the Pupipara (Melophagus) 686
SUMMARY OF THE FACTS AND SUGGESTIONS AS TO THE CAUSES OF METAMORPHISM 705
Theoretical conclusions; causes of metamorphosis 708
POSITION OF INSECTS IN THE ANIMAL KINGDOM
Although the insects form but a single class of the animal kingdom, they are yet so numerous in orders, families, genera, and species, their habits and transformations are so full of instruction to the biologist, and they affect human interests in such a variety of ways, that they have always attracted more attention from students than any other class of animals, the number of entomologists greatly surpassing that of ornithologists, ichthyologists, or the special students of any other class, while the literature has assumed immense proportions.