SEA-ANEMONES: THEIR WEAPONS 417 _ 



was not until after many observations that I detected them; 

 in an example from T. crassicornis, which had discharged 

 about half of the wire, I have not seen the slightest sign 

 of armature on the ecthorceum. So far as my investiga- 

 tions go, these Spiral Cnidse are confined to the walls of 

 the tentacles, in which, however, they are the dominant 

 form. ' ' 



Such, then, is the form and armature of these organs. 

 But I have not yet done with them. The emission of the 

 wire, strange to say, is a process of distinct eversion from 

 beginning to end. The eclkor&um is not a solid, but a 

 tubular, prolongation of the walls of the cnida, turned-in, 

 during its primal condition, like the finger of a glove 

 drawn into the cavity. Of this fact you may convince 

 yourself by a careful watching of the phenomena before 

 you. Many of the ecthorcea from the tangled cnidce now 

 under your eye run out, not in a direct line, but in a 

 spiral direction. Select one of these, and you will per- 

 ceive that each bend of the spire is made, and stereotyped, 

 so to speak, in succession, while the tips go on lengthen- 

 ing; the tip only progresses, the whole of the portion 

 actually discharged remaining perfectly fixed; which could 

 not be on any other supposition than that of evolution. 



In the discharge of the chambered kind to revert to 

 those which we were just now examining we saw the 

 ventricose basal part first appear; the lower barbs flew out 

 before the upper ones, and all were fully expanded before 

 the attenuated portion began to lengthen. "This, again, 

 is consistent only with the fact of the evolution of the 

 whole. On several occasions of observation on the cham- 

 bered cnidce, of Cyathina Smithii, I have actually seen the 

 unevolved portion of the ecthorceum running out through 



