Fission and Gemmation in the Animal Kingchm. 45 



which some years ago were stated by Semper to occur in 

 certain Stony Corals ■^, it is to be remarked that some of 

 them, in so far as the facts, wliich were principally derived 

 from the skeletons, admit of such an interpretation at all, 

 must be referred to processes conformable to the Strobila- 

 formation of the Medusce, i. e. must be regarded as cases of 

 fission. This applies especially to Flahellum variahile and 

 PlacotrocJius Icevis. But as to Semper's statements about the 

 asexual reproduction of his species of Fangia (which are not 

 more closely s])eciHed), they have so little to do with adequate 

 observations that a close investigation, particularly of the 

 processes of growth as they occur in these forms, will have 

 to be undertaken afresh before a satisfactory insight will be 

 possible. 



The numerous modes of reproduction in the Annelids, some 

 of which are more thoroughly, but the greater portion only 

 very su]:)erficially, known f, cannot be here discussed. Thus 

 much, however, may be affirmed without immediate proof, 

 that, so far as regards observations and not theories, gemma- 

 tion has hitherto not been shown to exist with certainty in 

 the segmented worms, with the exception of the peculiar 

 budding form of Si/IIis ramosa. The pretended lateral gem- 

 mation of certain Annelids, which Pagenstecher| believed he 

 liad observed, has already been rejected by Ehlers § as erro- 

 neous. It is true that the asexual reproduction of Autolytus 

 pi-olifer^ which was observed years ago by Frey and 



* C. Semper, "Ueber Generationsweclisel bei Steinkorallen &c.," 

 Zeitschr. f. wiss. Zool. Bd. 22, pp. 235 et sqq. 



t This applies especially to the reproduction of Myrianida (Myria- 

 dina) described by Milue-Edwards (" Recherches zoologiques faites pen- 

 dant iin voyage sur les cotes de la Sicile," Ann. Sc. Natur. (ser. 8), Zool. 

 t. iii. pp. 170 e^s^y ). With regard to this M. Scbultze says, "As a 

 matter of fact, as is evident from his description, Milne-Edwards observed 

 only a single specimen, which consisted of a series of seven individuals 

 adhering to one another. From the series in question this investigator 

 formulated his views as to the nature of the fission, which he supposed to 

 be based upon a true formatiou of buds. But how difficult it is to decide 

 from such scanty material, and without the closest microscopical inves- 

 tigation, whether a segment of the parent-form does or does not pass into 

 the young, will be admitted by every one who has occupied himself with 

 similar observations " (M. Schultze, " Ueber die Fortpflauzung durch 

 Theilung bei Nais 'proboscidea^'' Arch. f. Naturgesch. lo Jahrg., Bd. 1, 

 p. 302). The numerous and scattered statements as to cases of ase.xual 

 reproduction in Annelids altogether urgently need a critical sifting, in 

 order to separate the observations from the speculations. 



t A. Pagenstecher, '* Untersuchungen iiber niedere Seethiere aus 

 Cette," Zeitschr. f. wiss. Zool. Bd. 12, p. 267. 



§ E. Ehlers, ' Die Borstenwiirmer,' Leipzig, 1864-1868, pp. 21 1 et sqq. 



