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. 

 Ccelenterata. General. 



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

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



(146) O. and R. Hertwig. Der Organismus d. Medusa; 11. seine Stellung z. 

 Keimbldttertheorie. Jena, 1878. 



(147) A. Kowalevsky. "Untersuchungen lib. d. Entwicklung d. Ccelente- 

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

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

 d. Anat. 11. Phys. (Hoffman u. Schwalbe), 1873. 



Hydrozoa. 



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

 America. Boston, 1862. Vol. iv. 



(149) G. J. Allman. A Monograph of the Gymnoblastic or Tnbiilarian Hydroids. 

 Ray Society, 1871-2. 



(150) G. J. Allman. "On the structure and development of Myriothela." Phil. 

 Trans., Vol. CLXV. p. 2. 



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

 considered sous le rapport physiologique, embryogenique, et zoologique." Nouv* 

 Mem. de FAcad. de Brux., Tom. xvn. 1844. 



(152) P. J. van Beneden. " Recherches sur I'Embryog&iie des Tubulaires et 

 1'histoire naturelle des diffe'rents genres de cette famille qui habitent la Cote d'Ostende." 

 Nouv. Mem. de I' 'Acad. de Brux., Tom. xvn. 1844. 



(153) C. Claus. " Polypen u. Quallen d. Adria." Denk. d. math.-naturwiss. 

 Classed, k. k. Akad. d. Wiss. IVien, Vol. xxxvin. 1877. 



(154) J. G. Daly ell. Rare and Remarkable Animals of Scotland. London, 

 1847. 



(155) H. Fol. "Die erste Entwicklung d. Geryonideneies. " Jenaische Zeit- 

 schrift, Vol. vn. 1873. 



(156) Carl Gegenbaur. Zur Lehre vom Generationswechsel und der Fort- 

 pJJanzung bei Medusen und Polypen. Wiirzburg, 1854. 



