THE WAYS OF LIFE 237 



will be clothed in green '. In an aquarium divided into two 

 with different colours (red and green), he placed crabs 

 which had in a preparatory aquarium clothed themselves 

 with red and green. The red crabs went towards the red 

 end, the green crabs towards the green end. In an aquarium 

 divided into three equal parts, the middle one white, the 

 other two black, the white crabs went to the white part 

 and remained there. In a control experiment in another 

 aquarium, with black in the middle and white on both sides, 

 the black crabs went for the black. 



That the facts are suggestive of active masking and of 

 deliberate choice must be granted, but Minkiewiez pointed 

 out the danger of hurrying to a generous conclusion. He 

 refers to FoPs observation that crabs could be got to put 

 on a dress of white paper, which made them more, not less, 

 conspicuous. He points out that clothed crabs transferred 

 to an aquarium of a very discordant colour make no 

 attempt to remove their old costume, though they hang 

 on new papers beside the old ones. Furthermore, he found 

 that crabs put into a black aquarium never took black 

 paper if they could find any other colour. ' They cover 

 themselves with green, red, or white, making a bright 

 patch on the black floor of the aquarium, instead of con- 

 cealing themselves '. The apparent contradiction between 

 these exceptional facts and those which suggest deliberate 

 self-disguise is very striking, and it led Minkiewiez to 

 inquire carefully into its significance. 



He found that blinded crabs disguised themselves at 

 once, though without any reference to the colour of the 

 surroundings. Whenever their claws touch suitable things 

 the routine of reflex movements begins, their mouth- 

 appendages are next touched, and then the dorsal hooks. 



