ORIGINS OF AGAMIC PATTERNS 



6ii 



attachment. Except for this group of cilia the larvae appear to be com- 

 pletely radial (Fig. 192, B, C). Larvae of this type are free-swimming. In 

 still other larval forms the original polar axis, indicated by the disk of 

 attachment, is oblique to a dorsiventral pattern; consequently, bilateral- 

 ity is present, but a different bilateraUty from that mentioned above 

 (Fig. 192, D), in that the polar axis tends to become physiologically an- 

 teroposterior while in the other type it is physiologically dorsiventral and 



B 



D 



Fig. 193, J-E.—Larval development from internal buds in Suctoria. A, B, two stages of 

 bud development in Tokophrya cyclopum, dividing meganucleus in B.; C, Choanophrya inftindib- 

 ulifera with one larva free in cavity, a second developing, and perhaps a third in still earlier 

 stage; D, early stage of Pseiidogemma fraiponti; E, Acineta tuberosa (after Collin, 1912). 



at right angles to the anteroposterior axis. As regards the variety of axial 

 relations, these larval forms resemble somewhat the types of axiate pat- 

 tern in echinoderms. 



Origin and development of the larval forms from the suctorial form 

 differ in different species and in some seem to differ from anything known 

 in other groups. Larvae of many species develop from "internal buds" in 

 a cavity of the parent body (Fig. 193). According to various authors, 

 their development in certain species shows two features of particular in- 



