author's abstract of this paper issued 

 by the bibliographic service, mat 4 



LONGITUDINAL FISSION IN ACTINIA BERMUDENSIS 



VERRILLi 



A. C. WALTON 



Bermuda Biological Station for Research 



EIGHT FIGURES 



Longitudinal fission has long been recognized as a normal means 

 of non-sexual reproduction among sea anemones. McCrady 

 ('58)- observed aboral-oral fission in Actinia cavernosa, and 

 G. C. Davenport ('03) observed similar phenomena in Sagartia 

 luciae. In these cases fission was by constriction, followed by 

 rupture. Carlgren ('93) in Protanthea simplex, and Torrey 

 ('98) in Metridium found an aboral-oral fission by constriction 

 without rupture. Mrs. Thynne ('59) observed a side-to-side 

 fission accompanied by rupture in the case of Cyanthina smithi. 

 Torrey and Mery ('04) show that all three of the above methods 

 are normally found in Sagartia davisi, with the plane of divi- 

 sion running perpendicular to the long axis of the mouth. 



It is especially in Metridium that the double condition has 

 been observed. Two-headed specimens had been noted as early 

 as 1775 (Dicquemare). Johnston ('47) stated his belief that 

 these conditions were due to the coalescence of two separate 

 individuals; but Gosse ('60) contended that such individuals 

 owed their existence to spontaneous division. Foot ('63) re- 

 corded the discovery of a specimen having two mouths on one 

 oral disc, but expressed no opinion as to the cause. Carlgren 

 ('93), like Gosse, contended that such forms were stages in a 



^ Contributions from the Bermuda Biological Station for Research, No. 87. 



^ For further literature see the following papers of Parker and Carlgren. 



Parker, G. H., 1899. Longitudinal fission in Metridium marginatum Milne- 

 Edwards. Bull. Mus. Comp. Zool., vol. 25, pp. 43-55, 3 pis. 



Carlgren, O., 1909. Studien liber Regenerations- und Regulationserschein- 

 ungen. IL Erganzende Untersuchungen an Actinien. Kongl. Svenska Veten- 

 skaps Akad. Handlingar, Bd. 43, No. 9, 48 pp., 4 Taf. 



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