Xll 



CONTENTS. 



Chapter XXVII. INSECTA— continued. 



6. The formation of the germ-layers . ... 



7. Further development of the mesoderm 



Development of the body-cavity . ... 



8. The formation of organs . . ... 



A. Outer integument . . ... 



B. Endo-skeleton . . ... 



C. The nervous system . . ... 

 I>. The sensoiy organs . . ... 



The ocelli . . ... 



E. The tracheal system . . ... 



F. The alimentary canal and intestinal glands 



G. Heart . . . ... 



H. The musculature, the connective tissue, and the fat-1 pody 

 /. Genital organs . . ... 



II. Metamorphosis . . . ... 



1. The larval forms .... 



A. Homomorpha . . ... 



B. Heteromorjiha . . ... 



2. Development of the imago . . ... 



A. Development of the external form of the body . 



B. Development of the internal organs of the imago 



Hypodermis . . ... 



Musculature . . ... 



Intestinal canal . . ... 



The tracheal system . ... 



The nervous system . ... 



The fat-body . 



The ultimate fate of the phagocytes 

 General considerations regarding the development of 

 the imago in the pupa . ... 



III. Parthenogenesis, Paedogenesis, Heterogeny . ... 



IV. General considerations . . . ... 



Literature ..... 



PAGE 



309 

 318 

 318 

 322 

 322 

 323 

 323 

 329 

 329 

 334 

 336 

 338 

 341 

 342 

 355 

 355 

 356 

 359 

 367 

 370 

 378 

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 381 

 382 

 385 

 3>6 

 3S6 

 386 



3>7 

 388 

 390 

 396 



Chapter XXVIII. 



GENERAL CONSIDERATIONS 

 ARTHROPODA 

 Formation of the germ-layers . 

 Appearance and further development of the organs 

 Nervous system 

 Eyes 



Respiratory organs . 

 Fore- and hind-guts . 

 Development of the enteron 

 Development of the mesoderm 

 Germ-band 



Embryonic envelopes, metamorphosis 

 Interpretation and relationships of the Arthrop i la 

 Literature 



ON THE 



Subjects Index 

 Authoks Index 



411 

 412 

 413 

 413 

 414 

 420 

 421 

 422 

 423 

 424 

 425 

 426 

 431 



433 



437 



