CCELENTERATA. 187 





resembling the adult is formed as a bud. The bud becomes 

 detached and then gives rise to a permanent sexual Fungia. 

 From the nurse-stock there is formed however a fresh bud at 

 the centre of the scar left on the detachment of the old one. 

 The fresh bud eventually becomes separated from the nurse-stock 

 leaving a small portion of its stem behind ; each succeeding bud 

 similarly leaves a small portion of its stem, so that the nurse- 

 stock eventually acquires a jointed appearance. In the above 

 process we clearly have, as in the Hydromedusae, a non-sexual 

 form the nurse-stock produced directly from the larva, giving 

 rise by budding to a sexual form ; all the conditions of an alter- 

 nation of generations are therefore fulfilled. It seems however 

 possible that the nurse-stock itself may eventually become sexual. 



BIBLIOGRAPHY. 

 C&lenterata. General. 



(145) Alex. Agassiz. Illustrated Catalogue of the Museum of Comparative 

 Anatomy at Harvard College* No. II. American Acalephae. Cambridge, U. S., 1865. 



(146) O. and R. Hertwig. Der Organismus d. Medusa u. seine Stellung *. 

 Kelmblattertheorie. Jena, 1878. 



(147) A. Kowalevsky. "Untersuchungcn lib. d. Entwicklung d. Ccclcnte- 

 raten." Nachrichten d. kaiser. Gtfell. d. Freunde d. Naturer kenntniss d. Anthro- 

 pologie u. Ethnographie. Moskau, 1873. (Russian.) For abstract vide Jahretberichte 

 d. Anat. u. Phys. (Hoffman u. Schwalbe), 1873. 



Hydrozoa. 



(148) L. Agassiz. Contributions to the Natural History of the United States of 

 America. Boston. 1861. Vol. IV. 



(14$) G. J. Al 1 man. A Monograph of the Gymnoblastie or Tubularian llydrrids. 

 Ray Society, 1871-2. 



(150) G. J. A 1 1 man. "On the structure and development of Myriothcla." rhil. 

 Trans., Vol. CLXV. p. i. 



(151) P. J. van Beneden. "Mem. sur les Campanulaires de la Cote d'Osteodt 

 conside"res sous le rapport physiologique, embryogcnique, et zoologique." AWw. 

 Mem. detAcad. de Brux. % Tom. xvu. 1844. 



(152) P. J. van Beneden. "Recherches sur 1'Embryogrfnic ties Tubulairo et 

 ITustoire naturelle des diffcrents genres de cette famille qui habitent la Cote d'Ostende." 

 AW. Mem. de F Acad. de Brux.* Tom. xvu. iS 44 . 



(158) C. Claus. "Polypen u. Cjuallen d. Adria." Dtnk. J. matk.-itatttnnss. 

 Classed, k. k. Akad. d. Wiss. Hit*, Vol. xxxvni. 1877. 



(154) J. G. Daly ell. Rare and Rtmarkablt Animals f &0OtuJ. London, 

 1847. 



(156) H. Fol. "Die erste Entwicklung d. Geryonkleneies. " Jenaixhe Zot* 

 sfArift, Vol. Vll. 1873. 



(156) Carl Gegenbaur. Zur Lehrt \m Gcneratwuwtchul **d der f*rt- 

 pflantung M Medustn und Poly fen. WUrzburg, 1854. 



