70 CLASS II. 



arms, when separated, grew into new Polyps ; an experiment which 

 did not succeed with TREMBLEY. The power of reproduction is 

 in Actiniae just as great ; they regenerate parts that have been cut 

 away, and admit of propagation by artificial division, as DICQUEMARE 

 especially has shewn by his experiments. 



Before leaving the propagation of Polyps, we must notice those 

 late observations which indicate so close an affinity between Medusae, 

 and certain Polyps, that in time probably a great revolution will 

 be made in the systematic arrangement of the animal kingdom. 

 In Syncoryne, for instance, and Coryne (Clava), and certain Cam- 

 panularice bell-shaped appendages or off-shoots have been noticed, 

 which at length are separated from the stem, and resemble minute 

 Medusse. Conversely, also, the observations of SARS and of VON 

 SIEBOLD have shewn that Medusae come from the egg under an 

 oblong form resembling that of infusories beset with cilia: these 

 move freely, at first, then fix themselves, lose their cilia, become 

 clavate, acquire arms, and perfectly resemble Hydra. These hydra- 

 like forms divide by transverse indentations, and separate into rings 

 from which Medusce arise. 



It is possible, therefore, that all hydra-form Polyps may be only 

 imperfect forms of Medusce. And if so, those animals which 

 RE'AUMUR first named Polyps, would no longer belong to this class. 

 But on this supposition it is wonderful that Spermatozoa should be 

 observed in Hydra and Coryne : a fact that may cause us to hesitate 

 before we conclude, with DUJARDIN, that the eggs, described above 

 (p. 68), are Bulbilli. At all events the perfect form of Hydra would 

 then be unknown 1 . 



1 We cannot detail these observations more particularly, without being diffuse 

 beyond our object. Let it suffice to refer the reader to Lov!$N Stockh. Vetensk. Akad. 

 Handl. 1836 ; WIEGMANN'S Archivfiir Naturgesch. v. 1837, s. 219 262, s. 321 326; 

 Ann. des Sc. not. sec. Serie. Tom. xv. Zool. pp. 157 176. (Observations sur le 

 developpement et les metamorphoses des genres Campanulaire et Syncoryne.) 



SABS, Beskrievelser og Jagttagelser over nogle maerkelige eller nije i Havel ved der 

 Bergenske Kyst levende Dyr. Bergen, 1835. 



C. TH. V. SIEBOLD, Neueste Schriften der naturf. Gesellsch. in Danzig in. 2 Heft 

 1839, s. 2635. 



SARS, Mem. sur le developpement de la Medusa aurita et de la Cyanea capillata. 

 Ann. des Sc. not. sec. Serie. Tom. xvi. Zoologie, pp. 321 348. 



STEENSTRUP om Fortplantning og Udvikling gjennem veodende Generationsraekker. 

 Kjobenhavn, 1842. 40. (Translated by G. BUSK for the Ray Soc. from the German 

 Translat. 1845, On the Alternation of Generations.) 



