t INTELLIGENCE, POWER, 



the conception that all animals are essentially electric in 

 nature, for if they were not so the sting ray could not have 

 been converted from a muscular to an electric mechanism. 



The brain of the sting ray, as stated, is large because each 

 of the ninety-four pairs of nerves emerging from the brain 

 has a mechanism of its own in the brain. For the same 

 reason, the brain of the electric ray is large, for each of the 

 muscles that has been converted into an electric cell has its 

 own mechanism in the brain. The ratio of body weight to 

 brain weight in the sting ray was 1 1209; that of the electric 

 ray was 1:441. The need of constant muscular-electric- 

 energy to maintain the sting ray and of electric energy to 

 maintain the electric ray is shown by the comparable 

 ratios of thyroid gland to body weight, 1 : 9989 for the sting 

 ray, 1 : 11897 f r the electric ray. 



Thus, on the shallow beaches where the water is richly 

 mixed with air, evolution raised the energy and increased 

 the size of the energy-controlling organs. The batlike ray, 

 living at the shallow edge of the sea, where the trade winds 

 blow and the waves ceaselessly mix the rich oxygen content 

 of the air with the water, has been adapted to a greater 

 supply of oxygen than is possessed by other fish. The 

 constancy of the tide and the trade winds brings about a 

 constancy of waves and foam. The trade winds being 

 constant, foam is constant, increased atmospheric oxygen 

 in the water is constant, and the larger brain and 

 higher metabolism of the sting ray, with its increased 

 muscular activity, are constant. Thus the tides and the 

 trade winds are responsible for the exceptionally large brain, 

 large heart, large thyroid gland, and rich blood supply of 

 the sting ray as compared to other fish. 



In the sting ray and Thomson's gazelle we have two ani- 

 mals far removed from each other a gill-breathing animal 

 and a lung-breathing animal, a cold-blooded animal and a 

 warm-blooded animal. The sting ray in his foamy habitat 

 has such an exceptionally high concentration of oxygen that 



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