Xll CONTENTS 



PAGE 



General considerations: interpretation of the Ortho- 



nectidse, etc 215 



Literature 215 



Chapter VI. Nkmertini. By E. Korschelt .... 217 



Oviposition ; different forms of development .... 217 



1. Development through the Pilidium larva . . . 217 



Blastula ; gastrula ; Pilidium 218 



Origin of the worm in the Pilidium .... 221 



2. Development after the type of Desor .... 224 



3. Direct development 227 



General considerations : interpretation of the various 



forms of development 229 



Belationships of the larvae and adult animals to other 



groups 230 



Literature 232 



Chapter VIL Nemathelminthes. By E. Korschelt . . . 234 



L Nematoda . 234 



Embryonic development 234 



Cleavage ; formation of the germ-layers .... 234 



Formation of the embryo 237 



The post-embryonic development ; Trichocephalus ; 



Heterakis 239 



Dochmius; Mermis 239 



Sphserularia ; Atractonema 240 



Heterodera ; Allantonema 241 



E/habditis nigrovenosa ; Rhabdonema ; Cucullanus . 242 



Dracunculus ; Spiroptera ; Trichina .... 243 



IL Gordiidse 244 



Embryonic and subsequent development . . . 244 

 General considerations : Gordiidae, Nematoda, and 



Acanthocephali 246 



Literature 247 



Chapter VIIL Acanthocephali. By E. Korschelt . . . 249 



Cleavage ; embryonal membrane 249 



Embryo and larva : their migration and further development 250 



Literature 255 



Chapter IX. Rotatoria. By E. Korschelt .... 256 

 Heproduction by means of summer, winter, and male eggs ; 



cleavage 256 



Formation of the germ-layers and further development . . 257 

 General considerations : Trochospheera sequatorialis, com- 

 parison with the Trochophore larva of the Annelida, etc. . 259 



Relationships to the Arthropod a (?) 260 



Literature 261 



Chapter X. Annelida. By E. Korschelt 262 



I. Chaetopoda and Archiannelida . ^ . . . 262 



