Xll CONTENTS 



General considerations; interpretation of the Ortho- 



nectidse, etc 215 



Literatui'B 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 develoi^ment ........ 227 



General considerations : interpretation of the various 



forms of development 229 



Relationships of the larvae and adult animals to other 



groups 230 



Literature . • 232 



Chapter VII. Nemathelminthes. By E. Korschelt . . . 234 



I. 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 



Hhabditis nigrovenosa ; Khabdonema ; Cucullanus . 242 



Dracunculus; Spiroptera ; Trichina .... 243 



II. Gordiidae .244 



Embryonic and subsequent development . . . 244 

 General considerations : Gordiidae, Nematoda, and 



Acanthocephali 246 



Literature 247 



Chapter VIII. 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 

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



cleavage 256 



Formation of the germ-layei's and further development . . 257 

 General considerations : TrochosphiBra aequatorialis, com- 

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



Relationships to the Arthropoda (?) 260 



Literaturti 261 



Chapter X. Annelida. By E. Korschelt 262 



I. Chaetopoda and Archiannelida 262 



