DIVISIONS OF THE HYDKOZOA. 



63 



bell-shaped disc, which is attached by its base to the parent organ- 

 ism, and has its cavity turned outwards. From the roof of this 

 disc there is suspended a kind of handle, which corresjMonds to the 

 clapper of the bell, and is termed the " manubrium " (Lat. for 

 handle). From the fixed or proximal extremity of the central 

 process or manubrium proceed four or eight canals, which extend 

 to the margin of the bell, where they all open into a circular canal 



Fig. 32.— Grnup of zooids of Hydractinm echinatct. Enlarged (after Hineks). a a Nu- 

 tritive zociids ; 6 i Generative zooids, carrying sacs tilled with o\'a (" sporosaos "). 



surrounding the mouth of the bell. This bell-shaped reproductive 

 bud may attain no higher development than this, and may remain 

 permanently attached to the parent organism from which it is pro- 

 duced. In other cases, howevei-, a higher state of tlevelopment is 

 reached. The generative bud or gonojihore (fig. 29, C) becomes 

 detached from its jjarent colony ; the manubrium or central process 

 develops a month at its free or distal extremity ; tlie mouth of the 



