224 ANIMAL COLORATION. 



that for a long time I took the corona of the Annelid for a 

 polyp, until by an accidental blow I caused all the Mijxicolm of 

 a large coral stock to shrink suddenly into their tubes, though 

 it was not severe enough to induce an equally rapid movement 

 in the polyps of the apathetic Cladocora. 



At the first moment I must confess I felt an almost childish 

 delight at having detected so flagrant an instance of protective 

 mimicry : here was a defenceless tube worm, evidently most 

 effectually protected by its resemblance to a polyp, well defended 

 by powerful weapons. However, I soon found reason to doubt 

 this interpretation of the facts ; why should the annelid re- 

 quire any such protection, since it could withdraw itself with 

 the swiftness of lightning into its tube embedded in coral, 

 where probably no enemy would be able to follow it ? Still, 

 the wonderfnlly complete resemblance between the two creatures 

 could not be disputed, nor could the fact that this resemblance 

 was perfectly normal. 



Among the hundreds of specimens of Mijxicola, which I 

 found in various pieces of coral, procured from the most various 

 localities, I never found one that had not these same points of 

 resemblance to the polyps. One day, finally, I found a marine 

 sponge in which hundreds of this same Mi/xicolu were living, 

 and in every jiortion of it their funnels of tentacles extended 

 just to the level of the surface of the sponge ; but the sponge 

 was coloured very differently from the annelid, so that these, 

 when protruded, were very easy to distinguish from the sponge. 

 I then sought for the Jtfi/.x-icolu in other spots, and succeeded in 

 finding it almost everywhere : in the rifts in rocks, and in the 

 sand, between marine plants or the tubes of other worms — in 

 short, everywhere — and wherever I examined it closely, it was 

 exactly of the size and colour of the polyps of Cladocora 

 caespitom. Mimicry, it is plain, is out of the question ; the 



