ZOOPHYTES. 339 



which subsists between the different parts. The singular 

 spinous skeleton ; the expanded membrane of the polypary, 

 with its beautiful internal network of tubes and delicate 

 peripheric prolongations ; the alimentary polypes, some 

 white and filiform, others thick, fleshy, crimson, or yellow 

 sacs, obligingly everted, to expose their interior to our 

 microscopic eye; the reproductive polypes, with their 

 richly coloured generative sacs ; the sessile generative 

 organs of the polypary ; the ophidian polypes, coiled in neat 

 spirals when at rest, but starting into furious action, like a 

 row of well-drilled soldiers, when injury is inflicted on the 

 body to which they are attached ; and, lastly, the tentacle 

 polypes, floating in the water like long and slender threads 

 of gossamer, or dragging up heavy loads of food for the 

 common good ; — these, together with the intimate relation 

 and sympathy subsisting between the polypary and its 

 associated organs, all combine to form an object of the 

 highest interest, and indicate that, in this fixed yet travel- 

 ling zoophyte, we have a type of structure transitional 

 between the dentritic Hydroidm and the more highly 

 organised Acaleph.* In the simplest acalephoid form, 

 such as the medusoid of Companularia [or Laomedea] 

 (which is nothing more than an extension of the polypary 

 specially organised for independent and motile life), we 

 have (as in Hydractinia) an expanded polpary, repre- 

 sented by the umbrella, and permeated by vascular tubes, 

 from the confluence of which last spring, at the centre, 

 the tentacular polypes, various in number ; and between 

 them the reproductive polypes, represented by the sessile 

 generative sacs." t 



You see here a jar, on the glass side of which are traced 

 a number of very fine white lines, barely discernible by 



* From the Greek moA^ (akalephe), a nettle, applied to animals 

 known under the common name of jelly-fishes and sea-nettles, from their 

 causing the sensation of stinging when handled. 



t Dr. Wright, op. cit. 



Z 2 



