ACTINIA PARASITICA. 161 



But a third instance was even more remarkable still ; it was the 

 case of an annelid, about three-quarters of an inch long. See fig. 5. 

 Its head is represented in fig. 6. The coil gently passed over the 

 lower rings of the worm's body. The eye could distinguish the 

 glisten of the ciliary apparatus as it seemed deceitfully to woo the 

 body of the worm, and the worm moved on wholly unaffected by the 

 contact ; but at last the thread reached the head, and brushed that, 

 and the worm then and there died. Not a capsule left the thread, 

 yet the worm was killed. I removed it from the water, but it hung 

 lifeless at the end of the forceps. 



There was but one worm of those I saw attacked (if it can be 

 called a worm) which was armour proof against this deadly foe, it was 

 one which I have endeavoured to draw at fig. 7. It was about 

 three-quarters of an inch long, and covered all over with cilia, and 

 seemed to meet brush with brush, and it passed by and over the 

 coil with perfect indifference. 



Now the attitude of the thread in fig. 2 has no doubt suggested 

 to the reader one, at least, of the uses which we may attribute to it, 

 and the above facts, taken together, certainly, I think, bear out the 

 idea that the thread is a fishing line — it destroys and it gathers in. 

 If an animal protests against the contact, it is caught in a confining 

 web of bewildering capsules and a maze of viscous fluid, which keeps 

 it a close prisoner beside the thread, to be drawn in with the thread 

 at the will of the actinia. If it remains quiescent it dies, either 

 torn to pieces or paralysed. The thread of the screw acts as a 

 ditch or duct, and the ciliary action sets up a strong tide of particles 

 along it ; but for the accidental and fortunate circumstance, how- 

 ever, that I had seen the threads radiating in the pool at Durlstone 

 Head, as already described, I should have hesitated to give this 

 character to the organ, but that incident satisfies me that * at 

 times, at any rate, its functions are those now attributed to it. 



The whole story of this Actinia is a most astonishing one — the fact 

 that it takes to a carriage at all, the fact that it and the crab also must 

 change carriages from time to time, as each successive shell proves too 

 small for them ; the instinct that makes it always leave the open- 

 ing of the whelk shell uncovered for the crab ; its possession and 

 use of the acontia ; the story told by Mr. Gosse* of the parasitica 



* " Actinologia Brit.," 115. 



