GERM CELLS OF COELENTERATES 



III. AGLANTHA DIGITALIS 

 IV. HYBOCODON PROLIFER 



GEORGE T. HARGITT 



Zoological Laboratory, Syracuse University 



III. AGLANTHA DIGITALIS 



THIRTY-FIVE FIGURES (THREE PLATES) 



STRUCTURE 



Aglantha is a member of the order Trachomedusae, to which 

 also belongs Gonionemus and other medusae. This order is 

 usually characterized as having no hydroid or polyp stage and 

 consequently not showing an alternation of generations, the egg 

 developing directly into a medusa. Perkins ('02) has shown 

 that in Gonionemus the egg forms a planula which becomes a 

 small hydra-like organism which is sedentary and has the gen- 

 eral form and habits of a polyp. From this polyp buds are 

 produced and these, on being liberated, form other independent 

 polyps. Perkins assumes the polyps to transform directly into 

 medusae, after a short period of budding; this transformation 

 was not actually followed. Since such a life history has been 

 established for one member of the order, it may be that others 

 display the same abbreviated and more or less transitory polyp 

 stage. The life history of Aglantha is not known; it may have 

 a polyp stage, or the egg may produce a medusa by direct 

 development. 



Aglantha has a tall, conical shaped bell with eight radial 

 canals extending from the stomach to the ring canal on the mar- 

 gin of the bell. Gonads are attached to the radial canals close 



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