80 THE EVOLUTION OF THE METAZOA 



their tentacles (even if it is developed in one pair of tentacles 

 only), the inclination to adopt the radial symmetry, and many 

 other minor morphologic phenomena which Haeckel could 

 find in his Hydromedusa Ctenaria ctenophora (with a very sug- 

 gestive name !), all these facts have helped to preserve the idea 

 firmly and faithfully which connects Ctenophora closely with 

 Cnidaria. And what has been the attitude towards those differ- 

 ences that are even more numerous and all -important? These 

 have simply been pushed aside while at the same time attempts 

 have constantly been made to connect these two animal types 

 by way of a common origin; yet these attempts have always 

 remained fruitless. When finally Haeckel's attempt with his 

 Ctenaria had completely failed, new assays wxre made in the 

 search for the ancestor in the hope to find it in the most remote 

 past. Thus Goette (1912) proposed, to derive the Ctenophora 

 from a common primitive form which was constructed ad hoc 

 and which he called a "Scyphula;" this "Scyphula" was freely 

 swimming and "binumeral" (''\wei:(ahli£^ ) (A fine example 

 of a "suitcase theory" [''Koffertheorie"]. Those scyphulae which 

 had remained in plankton developed into Ctenophora, and 

 those that had sunk to the sea bottom evolved into the sessile 

 scyphopolyps, first without a medusa stage. This artificial con- 

 struction could find no acceptance. Not very different from it 

 was the interpretation proposed by Heider (1913) who has 

 tried to derive Ctenophora— surprisingly enough by way of 

 neoteny— from the anthozoan larvae that had lived in the 

 pelagic zone. Heider believed that there was some larval element 

 in Ctenophora. 



It has been a sign of emergency when attempts have been 

 made to go even further back into an already completely in- 

 different past and when the most simply built planula, a modi- 

 fied "gastraea" which had lived in the plankton began to be 

 considered as a starting point for the evolution of all the lowest 

 invertebrates. In this way the question of the origin has been 

 completely watered down. This is how the problem of the 

 origin of Ctenophora, and thus of their relationship connec- 



