NEW INTERPRETATION OF CNIDARIA 229 



firstly the detailed problems (e.g. the new system of 

 Cnidaria and the position of Cnidaria in the natural animal 

 system, the probable origin of Cnidaria or the turbellarian 

 theory of Cnidaria) and secondly the more general problems 

 as, for example the origin of Metazoa, the origin of Turbellaria, 

 the relationship between Protozoa and Metazoa, the criticism 

 of Haeckel's theory of a blastea and of a gastraea, as well as 

 the idea of germ layers, the problem of mesoderm and of meta- 

 merization, the origin of the ontogeny and its further deve- 

 lopment together with secondary cellularization, the general 

 division of the animal world connected with a reconstruction 

 of the animal classification— all this connected with an objec- 

 tive discussion of the opposite interpretations. 



The New System of Cnidaria 



It will be our first task to construct a system of Cnidaria 

 which will be a truly natural system and which will agree with 

 the new interpretation of the origin and of the phyletic develop- 

 ment of Cnidaria. Since this is not the right place to discuss in 

 detail various taxonomic problems, we will limit ourselves to 

 an outline of the system as it appears in larger groups or 

 taxons. The division of Cnidaria (the corresponding system 

 category will be later defined) into three main groups remains 

 unchanged since it agrees well with facts; we only have to 

 change the sequence of these three groups into the direction 

 Anthozoa -> Scyphozoa -> Hydrozoa. With regard to the 

 relationship connections of these three groups with each other 

 we have to take into consideration two possibilities. It is pos- 

 sible either that both Scyphozoa and Hydrozoa had developed 

 independently from each other, from the Anthozoa; or that 

 Scyphozoa had developed from Anthozoa and that later these 

 Scyphozoa themselves had evolved into Hydrozoa, the 

 youngest representatives of Cnidaria. The second possibility 

 seems to be more probable since Scyphozoa appear, so to speak, 

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