54 



HARDWICKE'S SCIENCE-GOSSIP. 



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of 



Fig. 25. The Common Sea-fan (Gorgonia ftabellum),l nat. size. After Johnston. 



Fig. 26. Gorgone verticillaire, x 3. 



the branching stems like the leaf-whorls of a"verti- 

 eillate plant, we part with the fan model altogether : 

 this last looks so much like a Sertularia that but 

 for the high authority of the French author we 

 should have doubted if it really ought to be classi- 

 fied as a Gorgonia at all. 



The Sea-fans are compound polypes, and to render 

 the plan of their construction, and the nature of 

 their being, intelligible to our junior readers, we 

 must take a glance first of all at a solitary simple 

 polype, and then pass on to the composite forms. 

 Most of them are no doubt familiar with the com- 

 monest of all polypes, the " naked, free, solitary " 

 Hydra viridis, and they have perhaps heard how it 

 multiplies by " gemmation." Erom the body of the 

 founder of the family little bud-like processes 

 sprout, " which are soon observed to resemble the 

 parent in character, possessing a digestive sac, 

 mouth, and tentacula ; for a long time their cavity 

 is connected with that of the parent, but at last the 

 communication is cut off by the closure of the canal 

 of the footstalk, and the young polype quits its 

 attachment and goes in quest of its own main- 



