AND PERSONALITY 



The tiger shark is the most formidable member of the 

 fish family. It is an active and fierce fighter. It has a wide 

 range of activity and no protection such as carapace, sting, 

 or poison. The tiger shark is as much a free lance as the 

 lion, the wolf, or the hunting dog. 



In this comparison between the porpoise and the tiger 

 shark we have in the porpoise an example of adaptation to 

 the production of internal temperature and constant mus- 

 cular activity. This adaptation has taken the form of an 

 increase in the .size of the brain, the heart, the volume of the 

 blood and the thyroid gland, but not of an increase in the 

 size of the adrenal glands. It will be seen that such an 

 energy formula equips the porpoise with a mechanism for 

 compensating the rapid loss of heat in the water. The shark, 

 being cold-blooded, assumes the temperature of the water. 



Since the oceans and lakes and rivers communicate with 

 each other, the sea would seem to be the theater of the most 

 complete evolution of the mechanism upon which the intelli- 

 gence, power, and personality depend. 



In the preceding chapters we have shown that upon the 

 size of the brain, heart, blood volume, thyroid and adrenal 

 glands and sympathetic system depend the intelligence, 

 power, and personality of the mammals and the birds 

 already cited. It was especially significant that we found 

 that this ratio applies to the negatively evolved reptile. 

 We now find that this formula applies to fish likewise. 

 Consequently, we should expect to find that the formula 

 would apply also to the domestic animals and to the pri- 

 mates, including man. 



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