CONTENTS. 



XI 



Chapter XXVI. MYRIOPODA— 



3. The formation of the organs 

 The nervous system 

 The eyes 

 The tracheae 

 The protective glands 

 The alimentary canal 

 The enteron 



The stomodaeura and the proctodaeum 

 The mesodermal structures 

 The body-cavity, the blood-vascular system, the fat 



and the musculature . 

 The salivary glands 

 The genital organs 

 Genera] considerations 

 Literature ..... 



Chapter XXVII. IXSECTA. 

 I. Embryonic development 



By K. Heider 



body, 



1. Oviposition and the structure of the ripe egg . 



2. Cleavage and the formation of the blastoderm . 



3. The formation of the embryonic rudiment and the embryonic 



integuments . . ... 



A. General view of the germ-band and the germ-envelopes 



B. The distinction between the superficial and the im- 



mersed germ-band . . ... 



C. The distinction between the invaginated germ-band 



and the germ-band that has been overgrown by the 

 membranes . . ... 



D. Insects with invaginated germ-band 



E. Insects in winch the germ-band is overgrown by the 



amniotic fold . . : . . 



F. Transition forms between the two types of development 



of the germ-band . . ... 



G. General considerations . ... 

 4 Development of the external form of the body . 



A. Segmentation . . ... 



Stomodaeum and proctodaeum. Labium 



Extremities . . ... 



Nervous system and tracheal invaginations 



Transition to the definitive form of body 

 Completion of the dorsal part of the embryo and degenera- 

 tion of the embryonic envelopes 



Involution "through the development of a continuous 

 dorsal amnion-serosa sac . ... 



Involution accompanied by dorsal withdrawal of the 

 amnion only 7 . . ... 



Involution accompanied by dorsal withdrawal of the 

 serosa and complete separation of the amnion . 



Involution accompanied by the imputation of both 



embryonic envelopes . ... 



E. General considerations . ... 



B. 

 C. 

 B. 

 E. 



A. 



B. 



C. 



D. 



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