THE NEW GENEALOGICAL TREE 375 



Both the skin and the intestine receive a mesohyl layer with 

 muscles, nerves, etc. Later we will return to discuss again in 

 detail the products of the middle body layer and their destinies. 

 We are therefore fully justified in paying special attention to the 

 conditions of the middle body layer in our attempts to con- 

 struct a natural system of the animal world. 



In opposition to the numerous attempts that have been 

 made so far to construct a classification of the animal world 

 on the basis of the colonial theory and in agreement with the 

 hypothesis of an evolution along the line blastaea-gastraea 

 where a bifurcation in the sense Coelenterata : Coelomata 

 becomes necessary at the very beginning of the Eumetazoa, 

 we find the classification of animals considerably simplified 

 if we construct it on the basis of the plasmodium theory of the 

 origin of the Eumetazoa in the sense of a development along 

 the line Prociliata-Acoelia (Turbellaria). The adherents of the 

 colonial theory have been unable to identify any well-founded 

 and therefore probable phyletic relationship between the 

 Coelomata and the Coelenterata. On the other hand it is 

 possible to make a rational and probable interpretation of the 

 phyletic, systematic, and thus also of the taxonomic conditions 

 as they existed at the very beginning of the Eumetazoa and of 

 their subsequent evolution if we view them from the aspect 

 of the plasmodial theory and in combination with the new 

 interpretation of the phylogeny of the Cnidaria. We can 

 express the uniformity of the Eumetazoa both in their system 

 and in their taxonomy if we abandon the opposing pair 

 Coelenterata : Coelomata (which is actually identical with the 

 pairs Diploblastica : Triploblastica, and Radiata: Bilateria) and 

 if we place the Turbellaria at the beginning of the Eumetazoa. 

 The symmetrical condition which as a property of the animal 

 body has played so far an important role (which was unfortu- 

 nately only a negative one) will lose from now on its im- 

 portance. We have shown that in the Eumetazoa there has 

 never been any primary radial symmetry; that this symmetry 

 emerged more or less developed only in those animals which 

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