AND PERSONALITY 



part made of iron, Steinach found that, as he lifted the iron 

 stone from one position to another with a magnet, the fish 

 underwent gyrations accordingly. 



The flash energy of escape in fish is provided not by a 

 pair of adrenal glands serving the entire organism but by a 

 number of masses of adrenalin-secreting substances called 

 "chromafrm tissue." 



The Sting Ray 



The sting ray is a sedentary animal. Most of the year it 

 occupies a protected position, partly buried in the sands 

 of the shallow sea. Like the alligator and the crocodile, it 

 is a biologic trap. The nostrils and the wide transverse 

 mouth are placed on the flat undersurface of the head, but 

 the eyes are on the upper surface. These active centers 

 locate the brain, over which there is a sloping, carapace- 

 like cover, as smooth as a tight-fitting glove, that extends 

 over the entire disk. Because every part of the sea is hunted 

 over by the great and small carnivorous fish, the passive, 

 protected fish must have developed the most complete 

 negativity to escape. 



The sting ray, although partly buried in the sand, must 

 keep the margins of his flappers protected against the 

 chance of getting between the teeth of a voracious fish. He 

 must not allow the water to make an uneven surface 

 beneath him lest a small enemy creep under his flappers. 

 He must have the means of progression. We found in the 

 sting ray a unique nerve-muscular mechanism. Dissection 

 showed that each flapper of the ray is provided with 94 

 muscle plates several centimeters in width, extending in 

 depth down to the middle of the flapper, where there is a 

 partition of cartilage. These muscle plates extend from the 

 thickest part of the mid-line to the extreme edge of the 

 flapper. A fibrous film separates each plate from its neigh- 

 bor. These muscle plates are attached to the firm skin and 

 to the cartilage that divides the flapper longitudinally as 



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