POLYSTOMATOUS CONDITION OF CORDYLOPHORA. 



25 



number of tentacles upon their sides, which is not the case 

 with the specimens drawn in Fig. 1. 



Question three is suggested by some observations which I 

 made by snipping with scissors the oral cone of normal 

 hydranths. These observations demonstrate that there is a 

 very remarkable power of repair and what may be called 

 " polarity " in Cordylophora. When a cut is made along the 

 long axis of the hydranth the sides of the separated parts 

 almost immediately come together, and after twenty-four 

 hours both halves of the slit hydranth appear as complete 

 hydranths with oral cone and tentacles (Figs. 3 and 4). If 



the cut is made so long as to extend to the proximal end of 

 the hydranth experimented on, the two portions are in a 

 few days found to have developed each a distinct segment of 

 hydrocaulus surmounted by a complete hydranth. 



These facts lend support to the view that the supernumer- 

 ary oral cones observed in the fresh specimens from Victoria 

 Docks may be due to the injury of the parent hydranth by 

 the attack of some crustacean or to other mechanical injury. 



Other experiments which I made do not bear directly on 

 the production of polystomatous hydranths, but serve to 

 illustrate the reproductive power of the tissues of Cordy- 

 lophora. 



Some of the hydranths, with a bit of hydrocaulus, were 

 snipped off from a healthy colony and placed in a vessel 



