136 THE BARBED THREADS. 



water, on a frond of Fucus serratus. It is round and 

 united, but with a suture down one side." * 



A curious evidence of the efficiency of the thread- 

 capsules as weapons of offence has occurred to me. 

 I was examining the brilliant purple filaments of 

 Adamsia palUata, under a power of 200 diameters. 

 There was no pressure applied, but a considerable 

 number of the small capsules were spontaneously dis- 

 lodged. In the aquatic box which I was using, there 

 was, still affixed to one of the glasses, the sucker of 

 a Gibbous Starlet [Asterina gihbosa) that I had just 

 before been looking at. The ciliary action of the 

 Adamsia' s filament had been wheeling it round and 

 round, partly in contact with the sucker, and the 

 result was that a good number (a dozen or two at 

 least) of the thread capsules had shot their darts into 

 the sucker, and were seen sticking all around its edge, 

 their threads imbedded into its substance, even up to 

 the very capsules. I thus saw how readily these 

 barbed threads are projected into the flesh of any 

 offending animal ; and if they are accompanied, as is 

 probable, by a subtle poisonous fluid, they are doubt- 

 less very effective. 



The filament under pressure shows thread-capsules 

 in innumerable millions, forming the greatest part 

 of its substance. This immense number is probably 

 intended to meet the continual demand for the use of 

 the weapons during the life of the animal ; since, once 



* I find that A. palliata has the power of shifting its locality like 

 other A ciiniadce. Two young specimens that I had in an Aquarium? 

 crawled spontaneously from their shells, and attached themselves 

 the one to a stone, the other to a sea-weed frond. (Second Edition.) 



