the animal's skin. Each cell, or chromatophore, is 

 provided with muscular walls; contraction of the 

 walls causes the cell to diminish to a microscopic 

 dot, making it practically invisible; their expan- 

 sion, however, is followed by an enlargement of 

 the cell area fully to twenty-five times. There be- 

 ing several sets of these chromatophores — amber 

 colored, blue-green, and reddish-brown — and each 

 set having the power to expand independent of 

 the others or in conjunction with them, an extraor- 

 dinary range and variety of hues can be pro- 

 duced. These pigment cells function throughout 

 the life of the squid, and their activity can be 

 observed while the creature is still contained with- 

 in the egg. It has been supposed by some that they 

 may afford concealment for the owner. It is prob- 

 able that at one period in the history of the group, 

 concealment was the primary business of the 

 chromatophores; but at present they seem to func- 

 tion for a different purpose. The squid makes no 

 attempt to hide itself from its enemies or its prey 

 by simulation of its surroundings; on the contrary, 

 its chromatophores often betray its excitement and 

 make it exceedingly conspicuous. Sexual activities 

 are particularly prone to engender these exhibi- 



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