56 



HTDROZOA. 



been kept for some days in vessels of sea-water, 

 it often happens that the polypites drop from their 

 stalks. Soon, however, new polypites are budded 

 forth, each having usually a smaller number of 

 tentacles than its predecessor. Similar are the 

 results produced by artificial fission. In this 

 manner, by section of a single stalk. Sir J. Gr. 

 Dalyell obtained, in the course of 550 days, twenty- 

 two successive polypites. 



Sertularidje. In most Corynidce, the course 

 of development closely corresponds with that above 



Fiff. lo. 



Development of Campanulaeia : — a, Campanularia Lovem; h, 

 oneof itsgonoblastidia from whose summit project two medusiform 

 gonophores, one of which is giving exit to a ciliated embryo ; c, 

 the same embryo, in its free swimming condition ; d and f, suc- 

 cessive stages of the young ccenosarc developed therefrom ; /, 

 medusiform zooid of Campamdaria dichotoma ; — ir, polypite; tt', 

 hydrotheca ; p', gonoblastidium. (a and / are about twice the 

 natm-al size; the others are much magnified.) 



described as taking place in Cordylophora. Of a 

 similar character, in its more general features at 



