NEW INTERPRETATION OF CNIDARIA 331 



As in the case of Metaphyta, nobody (as far I know) has 

 tried to derive the Spongiae from some polykaryonic ancestors ; 

 the colonial "spirit" of the Spongiae is much too obvious. The 

 difference which exists in various interpretations of the origin 

 of Spongiae are centred exclusively around the problem wheth- 

 er we can consider that Spongiae have a common origin 

 with other Metazoa (Eumetazoa), or whether they evolved as 

 a special type of polycellular animals from the colonies of 

 specialized Flagellata, the Choanoflagellata. Originally, zoo- 

 logists, who all came under the influence of ideas of Leuckart 

 and Haeckel, were inclined to believe that the Spongiae do not 

 represent an extra type, that instead they were genuine Gastra- 

 eadae. Numerous and important differences that exist between 

 Spongiae and other Metazoa w^ere noticed, yet again those 

 differences were attributed to diverging evolutions which had 

 started from a common origin (the primitive polyp). Scholars 

 soon became perplexed when they found (Metschnikoff, Sollas, 

 Delage, and others) that the greatest differences occur in just 

 the earliest ontogenies; the interpretation has therefore been 

 more and more widely accepted which sees in Spongiae a 

 special case among the polycellular animals. In the system of 

 the animal kingdom they were therefore separated as Parazoa 

 (Sollas) or as Enantiozoa (Delage) not only from the Coelente- 

 rata but also from all the other Metazoa, the Eumetazoa. 

 Nobody has found any objection to the fact that a cleavage 

 occurs in the ontogenies of Spongiae in the same way as in the 

 Volvocales and in the Eumetazoa. 



This situation is definitely solved, when the derivation of 

 the Eumetazoa from the colonies of Flagellata is generally 

 accepted. Objections, even if not supported by any very 

 important and convincing newly discovered facts (the sup- 

 posed discovery of nerve cells in Spbngiae by O. Tuzet and 

 by her school cannot be considered as a sufficient proof) 

 have suggested that the Spongiae had a common origin with 

 the remaining Metazoa and that the differences which exist 

 between the Spongiae and the remaining Metazoa were not 



