NEW INTERPRETATION OF CNIDARIA 251 



our research from two completely diflerent starting points and 

 motivated by two different aims. Jagersten wishes to improve 

 and therefore to save the old concept, and in this he finds 

 an obstacle in the old interpretation of the evolution of 

 Cnidaria; this induces him to reverse the direction of the 

 evolution of Cnidaria. I, on the other hand, have started 

 my research with a study of Cnidaria; facts which had 

 already been known have induced me to submit to a revision 

 of the connections that exist first among the Cnidaria them- 

 selves, which was followed by a study of the relationship 

 connections among Coelenterata, and finally among Metazoa. 

 Ultimately, this has led me to a new interpretation of the evolu- 

 tion of the animal world. As a result I have found that it has 

 become necessary to make much more radical char ges in 

 the present interpretations (starting with a reform of the 

 system of Cnidaria) than those changes that have been propos- 

 ed by Jagersten and by other well-known zoologists. 



Jagersten, and Remane before him, have only made the 

 situation increasingly worse. This has happened in such a way 

 that on one hand the contrast between a primary mesenchyme 

 and a secondary coelothelium (mesoderm s.str.) which was 

 previously quite unpleasant, has now become all the more 

 acute; and, on the other hand, the uncertainty regarding the 

 groups of Ameria which do not possess an actual coelom 

 s. str. (perigastrocoele) and even less a metameric perigastro- 

 coele has become all the more evident. Jagersten could not, 

 as it seems, accept unreservedly a solution, dictated by this 

 situation, of a large scale retrogressive evolution while at the 

 same time Remane finds himself obliged to admit such a 

 possibility. Jagersten remains silent about all this while at 

 the same time he promises a special study; yet to the best of my 

 knowledge no such study has not appeared so far. It would have 

 been better if Jagersten in order to remain consistent, had gone 

 further and connected his bilaterogastraea with the Entero- 

 coela, since it is clear that Annelida are Ecterocoela. It is 

 improbable, because it is unfounded, that a retrogressive 



