NEW INTERPRETATION OF CNIDARIA 311 



Eumetazoa (which is particularly true for the middle body- 

 layer, the mesohyl!); their tissues show a strong inclination 

 to a return into the plasmodial state which we usually call a 

 syncytium. 



An even more important difference between the polycellular 

 plants and sponges on one hand and the Eumetazoa on the 

 other, a difference which became evident above all during 

 the subsequent destiny of the phyletic development, is the 

 fact that such a degree of unity can never be reached by the poly- 

 cellular bionts by way of a colonial formation, as is the unity 

 that has been reached by the Eumetazoa. The latter had 

 inherited from the very beginning a uniform and already 

 comparatively highly developed organization from their pro- 

 tozoan ancestors, as far as such an organization could be 

 developed within the framework of a mono- or paucinu clear 

 state. The objections made by those scholars who adhere to 

 the old interpretation which considers that all the polycellular 

 organisms had evolved from colonies of cells — among 

 these scholars we mention above all Sachwatkin (1956) and 

 his intensive and extensive work— cannot deny the fact that 

 a great difference exists between the organizations of Spongiae 

 and of the Eumetazoa, even if we take into consideration the 

 sedentary way of life only (e.g. a comparison with the Hydro- 

 idea). Neither can they abrogate the difference that exist bet- 

 ween a sum of choanoflagellates where each member still 

 continues to exist as an individual which must first become 

 adapted to the "new conditions," and, on the other hand, 

 an infusorian with various organelles and generally fine struc- 

 tures which evolves in a direct line into progressively higher 

 Eumetazoa while at the same time the unity of the animal 

 is constantly preserved. 



There can be no doubt that a new form can develop by 

 way a coenobium from originally independent "monocellular" 

 protozoic or protophytic individuals; the development goes 

 from the state of coenobium via a formation of a colony or of 

 a cormus to that of the final form. Such a development can 

 21* 



