318 G. H. PARKER 



4. INDEPENDENCE OF PARTS 



Enough has already been said to make it quite clear that 

 many of the parts of Corymorpha are quite independent of the 

 rest of the polyp in their capacity to respond to stimuli. Thus 

 the stalk of Corymorpha will shorten and even localize a stimu- 

 lus applied to one side of it with as much success after the hy- 

 dranth has been removed from it as when the polyp is completely 

 intact. There is, therefore, no reason to suppose that the 

 hydranth contains nervous centers that are in any way essential 

 to these responses. 



In a similar way the separated hydranth exhibits on stimu- 

 lation movements in its distal and proximal tentacles and its 

 proboscis that are in all respects counterparts of the move- 

 ments of these organs in the polyps as a whole, showing that 

 the hydranth is in no sense dependent upon the stalk for its 

 neuromuscular activity. The separate hydranth as well as the 

 separate stalk can be anesthetized with chloretone or magnesium 

 sulphate and, after having thus lost their responsiveness, these 

 parts will separately recover when placed in pure sea-water. 



When the proboscis of a Corymorpha is cut off, the attached 

 distal tentacles continue to exhibit spontaneous movements and 

 turn vigorously away from the mouth on stimulation as they 

 do on the intact animal, activities that they lose temporarily 

 on anesthetization. The proximal tentacles also exhibit great 

 independence. If one is cut from a hydranth, its curved form 

 brings it to rest on the bottom of a glass vessel on its side and it 

 is comparatively easy to determine by the direction of its curve 

 -which is its oral and which its aboral face. On stimulating it 

 mechanically, it shortens slightly and curls orally as an attached 

 tentacle does. The same is true when it is stimulated by a 

 faradic current. Under this more favorable method of stimula- 

 tion a proximal tentacle that had a length of twelve millimeters 

 when at rest shortened to ten on stimulation and curled to a 

 half circle. These reactions disappear after the isolated tenta- 

 cle has been for five minutes in sea- water containing chloretone 

 and reappear on transferring it for three minutes to pure sea- 

 water. 



