276 Prof. E. Ehlers on the Interpretation 



Besides the phenomenon known since Daly ell's time *, 

 that fragments separate from the body of an Actinia and 

 become developed into young Actinia, we know of sponta- 

 neous processes of division in polyps with and without hard 

 parts, and some produced by external injuries, so that we are 

 led to believe that spontaneous divisions may be caused or 

 hastened by external influences. Bennet f has described the 

 spontaneous process of division, effected in three hours, of an 

 AntJiea cereus] this process is somewhat different from that 

 in which the usually incomplete division is preceded by the 

 formation of new organs, such as a buccal aperture. Lacaze- 

 Duthiers | obtained CaryophylUce which in collecting had been 

 split longitudinally, and kept them alive in this condition for 

 two months. Semper § has described the most singular pro- 

 cesses of division of corals belonging to the genus Diaseris^ 

 and thinks that here the breaking-up of the lobate forms 

 might be favoured by external influences. Whether in the 

 first two cases the spontaneously-formed or artificially-pro- 

 duced fragm.ents are able to regenerate themselves I cannot 

 say ; the portions observed by Bennet produced by sponta- 

 neous division appear to have completely closed their wounds, 

 but whether perfect union took place was not ascertained by 

 anatomical examination ; experiments which I formerly made 

 in this direction upon Actinise in aquaria furnished no results. 

 That, as in the instance described by Lacaze-Duthiers, 

 divided polyps remain alive for a long time, is in agreement 

 with the well-known tenacity of life in many of these animals. 

 The case of Folyparium ambulans, which now occupies us, is 

 approached more nearly by the observations communicated 

 by Semper [l. c), especially that of a Fungia, which is figured 

 by him on pi. xxi.fig. 4. In this instance the fragment of a 

 Fungia was separated by force from the whole, a fragment 

 with transversely-placed septa, which may be compared with 

 Polyparium amhulans with its transverse partitions. On the 

 margins of this fragment the animal regenerated itself with 

 formation of new buccal apertures. 



Under such circumstances the fragment of a polyp without 

 a buccal aperture would be more likely to remain " astoma- 

 tous " and to close the wounded surface by cicatrization, if the 

 widely-opened tentacles retained upon it rendered inception 

 of nourishment possible ; nay, under certain conditions, to be 



* 'Rare and Remarkable Animals of Scotland/ toI. ii, (1848), p. 232. 

 t ' Proceedings of the Natural-History Society of Dublin,' vol. iv. 

 (1884), pp. 208-212. 



\ 'Archives de Zoologie experimentale,' tome vi. (1877), p, 382. 

 § Zeitschr. wiss. Zool. Baud xxii. (1872), p. 269, 



