On Sjjontaneous Division in the Radiata. 391 



XLVIII. — On Spontaneous Division in the Echinodennata 

 and other Radiata. By Dr. C. F. LiJTKEN. 



[Concluded from p. 337.] 



Dalyell* and Semper fliave investigated the faculty of 

 regeneration in the Holothurida; and the former has established 

 that a voluntary spontaneous division really takes place at 

 least in some species of those Echinoderms. It is to be regretted 

 that with regard to the faculty of regeneration and to artificial 

 division we do not yet possess any methodical observations 

 upon other Echinoderms, especially the Asterida and Ophiu- 

 rida, in which the frequent cases of regeneration which have 

 been observed lead us to deduce the possibility of artificial 

 division if it were tried. But even if this were the case it 

 would not prevent our interpreting the phenomena already 

 described as a natural or spontaneous binary or radial division, 

 seeing that we are not in a position to discover an exterior in- 

 fluence capable of exerting upon the life of these animals so 

 profound and singular an action, but we can only seek the 

 cause of these natural phenomena of division in an act 

 emanating from the organism itself and having multiplication 

 for its object. 



Like the authors who have treated before me of heteractinism 

 in the Ophiurida and Asterida, I must therefore hold to the 

 hypothesis that in the cases already specially examined ( Ophio- 

 tJielttf Ophiactis (p.p.), Ophiocoma (p.p.), Asterias (p.p.), 

 Linckia (p.p.)? ^i^cl Ophidiasler (p. p.)) it is due to a true 

 spontaneous division, no doubt repeated several times. But, as 

 I have already pointed out, however acceptable this explanation 

 may appear, it cannot be regarded as the true one until it has 

 been verified upon animals kept alive for a long time in aquaria. 

 Nevertheless it has so many probabilities in its favour that 

 it is well to call attention to it — especially at a time when 

 " experimental zoology" already possesses a review of its own, 

 and the establishment of zoological stations is being realized 

 on the shores of that very sea which harbours two of the 

 species in which we suppose such a division to occur, namely 

 Ophiactis virens and Asterias tenuispina. If we could succeed 

 in keeping these species alive for a long time in aquaria, it 

 would no doubt be easy to settle the following points — namely, 

 whether a natm-al division really takes place, whether it is 

 repeated several times, whether it ceases when the animals 

 attain a certain age or size and when the organs have acquired 

 a certain degree of development, &c. These phenomena possess 



* Powers of thr Creator, vol, i. pp. 49 ct xeqq. 



t Reisen im Archipel der riiilippinon, 2ter Theil: Band i. p. 201. 



