VI 



The relationship between conjugation and copulation 280 



The pomf of separation of the evolutions of Infusoria and 



Eumetazoa 298 



The origin of the complex, hypercellular individualities 305 



Is the pl-ii;modial state of the Acoela a primary element? 314 



An attempt to reconstruct the initial state of the Eumetazoa. . . 319 



The origin of the middle body layer of the so-called mesoderm 321 



Tu'O difficulties of the theory of polykaryonts 329 



Can cleavage be really considered as a proof of the colonial theory? 335 

 The basic principles that should be used in a reform of the whole 



animal system 337 



Evolution generally had a progressive trend 346 



Chapter 4. The Classification of the Animal World and the 



New Genealogical Tree 352 



General premises 352 



The limit between the plant and the animal worlds 352 



The system of the Protozoa 357 



The transition from the Protozoa to the metazoan state 361 



There are no well-warranted Mesozoa 366 



The classification of Metazoa 368 



The Parazoa as an independent subregnum 368 



The Eumetazoa and their subdivisions 372 



The elimination of the terms Coelenterata-Coelomata 372 



The Coelomata as a taxonomic unit 384 



The first phylum of the Eumetazoa: The Ameria 391 



The transition from the amerous to the polymerous state .... 397 

 The problem of justification of the high taxons: Protostomia- 



Deuterostomia 407 



The classes of the Polymeria 411 



The phylum Oligomeria and its classes 421 



The sphere of the phylum Oligomeria 423 



The problem of the inclusion of the Sipunculida into the phylum 



Oligomeria 431 



The Oligomeria as the initial form for the evolution of the 



Chordonia 437 



The fou*th and the last phylum of the Eumetazoa: Chordonia 441 



The probable origin of the Chordonia 447 



A comparison of the present attempt to derive the Chordonia from 

 the ancestral form resembling the present day Enteropneusta 



with the similar attempt made b)'^ Hans Steiner 452 



The genealogical tree of the Chordonia 455 



The genealogical tree of the entire animal world 457 



An attempt to unify the animal system 461 



Bibliography 467 



Index 483 



