INTELLIGENCE, POWER, 



The fifth biological principle, that natural selection gave 

 to each wild animal larger adrenal glands than thyroid 

 gland, expresses the necessity of crisis energy mobilized by 

 the hormone of the adrenal glands in addition to the con- 

 stant energy mobilized by the hormone of the thyroid 

 gland. 



We have found the adrenal-gland-celiac-ganglion domi- 

 nance to be most marked in the cat family and the rodents, 

 in which both attack and defense depend on outburst 

 energy. The adrenal-gland-celiac-ganglion dominance is 

 less marked in animals requiring the long chase or long 

 escape, such as the wolf, the deer, and the antelope. 



In the evolution of wild animals, natural selection favored 

 the adrenal glands, celiac ganglia and plexuses. In man, 

 natural selection centered upon the thinking part of the 

 brain and the thyroid gland. The formula of a large brain, 

 large thyroid gland, absolutely and relatively smaller 

 adrenal glands, and variable celiac ganglia and plexuses is 

 that of a walking, thinking animal, namely, man. 



The formula of a brain smaller than that of man, a large 

 heart and volume of blood, large adrenal glands, and large 

 celiac ganglia is that of the thoroughbred horse. 



The formula of an extremely large brain, a large thyroid 

 gland, comparatively small adrenal glands, a moderately 

 large heart, and a strikingly large volume of blood is that 

 of the whale or the porpoise. 



The formula of a brain of lesser size than that of man or 

 the ape, a heart not so large as in the high-powered, long- 

 distance-running antelope, a moderate volume of blood, 

 large adrenal glands in comparison with the thyroid gland, 

 and celiac ganglia and plexuses as large as the adrenal 

 glands is that of the lion. 



Among the 284 species that we have dissected the lion 

 possesses the largest and most complex celiac ganglia and 

 plexuses. These structures we found to be the most distin- 

 guishing characteristic of the lion. 



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