CNIDARIA AS THE ONLY COELENTERATA 29 



in the present day, prove that we are still far from the ideal 

 solution. Many difficulties arise from this situation, especially 

 in the field of teaching. I tried to seek a redress to this 

 situation at the Fourteenth International Congress of Zoolo- 

 gists which w^as held at Copenhagen, and I proposed to find 

 a unified or compromissary animal classification which could 

 serve our practical purposes (Hadzi, 1956 a). Due to my 

 proposition a committee and president have been elected, 

 as yet without any further results. It is possible that this 

 attempt was made too early, or that it was discarded because 

 it was considered as being impracticable. 



Fortunately enough, the interest in the problem of phylogeny 

 and, in connection with this, of the construction of a truly 

 natural animal classification has been recently reawakened. 

 As an illustration I can mention the reaction which occurred 

 when my article appeared in Systematic Zoology (Hadzi, 1953). 

 It is perfectly natural that such reactions were not always 

 favourable, or, even constructive in regard to the new propo- 

 sition. It is not easy to convince those zoologists who have 

 been trained in long established concepts which they firmly 

 accept, that these old concepts are actually untenable. Max 

 Planck, if I am not mistaken, once stated that one is more 

 Likely to see the defenders of the old concepts die out before 

 becoming converted to new interpretations. It is now time 

 for the new generation, one free of tradition, to proceed 

 critically and make the decision. 



Some progress has nevertheless been made in the field of 

 phylogeny; this can be seen in the fact that the "variation 

 width" of hypotheses and theories, and thus of concepts, 

 has finally become somewhat narrower. An objective, even 

 if sharp, discussion can always be useful. 



In my opinion, in this area of biology one can arrive at 

 a new concept, at a new evaluation which has a synthetic 

 character, mainly along two lines. Either we succeed in making 

 a new discovery, a discovery of a brand new fact, e.g. of a 

 new fossil or of a living animal which has been unknown 



