Science2 - 00094

Science2 - 00094 - Untitled when they are placed on a quite...

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Untitled when they are placed on a quite artificial floor. As these fishes are very palatable and are much sought after by such enemies as cormorants and otters, it is highly probably that their power of self-effacement often saves their life. And it may be effected within a few minutes, in some cases within a minute. In these self-effacing flat-fishes we know with some precision what happens. The adjustment of colour and pattern is due to changes in the size, shape, and position of mobile pigment-cells (chromatophores) and the skin. But what makes the pigment-cells change? The fact that a blind flat-fish does not change its colour gives us the first part of the answer. The colour and the pattern of the surroundings must affect the eye. The message travels by the optic nerve to the brain; from the brain, instead of passing down the spinal cord, the message travels down the chain of sympathetic ganglia. From these it passes along the nerves which comes out of the spinal cord and control the skin. Thus the
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This note was uploaded on 10/05/2009 for the course MATH 205 taught by Professor Popescu,c during the Fall '08 term at UCSD.

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