NEW INTERPRETATION OF CNIDARIA 337 



The Basic Principles That Should Be Used 

 in a Reform of the Whole Animal System 



The necessity, or the unavoidable consequence, of chang- 

 ing the previous interpretations of the phylogenetic processes 

 of the animal world becomes self-evident when we summarize 

 the individual results of our study. They can be enumerated 

 as follows: 



(1) The evolution of Cnidaria had been mainly retrogressive 

 (it was partly progressive in a speciaHzing direction) because 

 of their sessile w^ay of life. This sessility of Cnidaria is a 

 secondary phenomenon. The evolution of Cnidaria did not 

 proceed in the direction Hydrozoa -> Scyphozoa -> Anthozoa 

 as this has been believed till now, but just in the opposite 

 direction. 



(2) The Cnidaria are not the most primitive and thus the 

 lowest Eumetazoa in spite of the fact that they have the 

 simplest structure. The most primitive Eumetazoa are in 

 reaUty the mainly plasmodial Acoela, among the Turbellaria. 



(3) The primitive Eumetazoa had not been radially sym- 

 metrical animals; they were instead bilaterally symmetrical 

 which was a consequence of their way of Hfe ; they were able 

 to move actively over a solid substratum. The radial sym- 

 metry had been developed secondarily as a consequence of 

 their sessile way of life which had been secondarily adopted 

 by them. 



(4) The Spongiae are a special group of Metazoa, they sho\^' 

 a special structural type, they have their ow^n way of feeding 

 and their own form of development. They must be definitively 

 separated from any connection with the other Metazoa, the 

 Eumetazoa. They stand thus as Parazoa between the Protozoa 

 and the Eumetazoa. They must be therefore excluded from 

 the group of Coelenterata. 



(5) The Ctenophora cannot be considered as Coelenterata. 

 Like Cnidaria they had evolved from the Turbellaria, yet 

 starting from their own root and parallel to the evolution 



