218 THE EVOLUTION OF THE META/COA 



colonies had been introduced by means of an imperfect budd- 

 ing or division ; frequently it is not easy to distinguish 

 budding from division. Even budding itself does not always 

 take place in such a way that one could distinguish between 

 extratentacular and intratentacular budding. As early as 

 in Anthozoa, i.e. in Octactiniae, development has led 

 to the formation of regularly excrescing and individualized 

 cormi as well as (even if in a moderate degree) to the poly- 

 morphism (dimorphism) of the polypoid individuals (subindiv- 

 iduals). 



All the three body layers participate, as much as this has 

 been known till now, in the budding of Anthozoa (the 

 so-called typical budding); this may also be true for Scypho- 

 zoa. As will be seen later, it is first in the Hydrozoa that so- 

 called atypical budding appears. In this the main role is 

 always played by those cells of the middle layer which are 

 usually considered as un-difFerentiated cells ; an interpretation 

 which was sharply contested by Steinbock (1954). We must 

 mention that in the higher types with a sessile way of life 

 of corms the budding always takes place in the so-called 

 atypical way, without participation of the endoderm. It has 

 already been mentioned that scyphomedusae which have a pre- 

 valent role among Scyphozoa do not reproduce asexually. 

 Transverse division appears regularly (even if not generally!) in 

 scyphopolyps, yet here it has become so specialized that nor- 

 mally polyps are not developed by way of transverse division, 

 only medusae. This transverse division which has become mul- 

 tiple can be so profuse and impetuous that it gives the impres- 

 sion of a terminal budding (the formation of the so-called poly- 

 discal strobilae). Lateral budding and the simultaneous for- 

 mation of colonies becomes rare. The buds of polyps which 

 grow directly on the maternal polyp or on the stolons, become 

 free and finally asexual reproduction is completely abandoned 

 (Lucernariidae, the hypogenetic species). The formation of po- 

 docysts develops in the secondarily solitarized scyphopolyps 

 which live in a shallow sea (Had^i, 1912); they represent a spe- 



