Crabs, Worms, and Fishes. 1 77 



and could only be detected by the most careful ob- 

 servation. The worms were of deep tints of olive 

 and yellow, and so on all through this floating city ; 

 the same brush, the same colours, the same artist had 

 been employed, each and every living creature being 

 in colour a mimic of the vast weed bed that consti- 

 tuted their floating home. 



The fact that I could not find the crabs and other 

 forms without difficulty, though they were floating 

 upon the surface, often in full view, suggested at 

 once that here nature had provided a wondrous pro- 

 tection, and that the inhabitants of the sargassum 

 were safe from their many enemies in their mimicry. 



But how was this condition obtained ? The crabs, 

 worms, and fishes of this mass of weed were not 

 always thus protected. We know that long ago or 

 in the past they lived elsewhere, and came as immi- 

 grants to the floating home, and were then in strik- 

 ing contrast to it. How then could this great change 

 have been produced ? Assuming that the crabs and 

 other forms have recently taken up their residence 

 here, we notice that they are not all alike in colour ; 

 there is a disposition to vary. Some are darker than 

 others, some lighter, some are spotted, and a few 

 perhaps resemble the colour of the weed. The latter 

 are accidents, freaks, just as in the case of the dogs 

 where perhaps one or two showed an abnormal de- 

 velopment of hair. In this instance man did the 

 selecting ; but in the case of the crabs it is a gull, or 

 many that are soaring over the weed in search of 

 food. The freaks or varieties which happen to re- 

 semble the weed, being inconspicuous, are not 



