INTELLIGENCE, POWER, 



quicker strike, a more powerful rush, a better game fish; 

 therefore a higher ratio of energy-controlling organs should 

 be found in the fish of the cold north and in the mountain 

 trout and salmon than in the sunfish, the sucker, and the 

 carp. 



The marine eye deals with dim light, which is concen- 

 trated on the retina by the large lens. The characteristic is 

 the wide pupil and the large size of the eye, which is set 

 prominently so as to catch the greatest amount of light. 



The most outstanding sense in fish is that of smell. The 

 olfactory lobe in fish may approach the rest of the brain in 

 size, and the olfactory nerves are the largest nerves in fish. 



This emphasis by evolution upon the olfactory sense is 

 easily understood when one considers that in terrestrial 

 animals, except in the case of man, the olfactory lobe is 

 highly developed in all the large mammals, in the ungulates, 

 and especially in the carnivores. The chemical emanations 

 that stimulate the sense of smell in the water are all- 

 pervading, as in the air, and the sense of smell is of even 

 greater value to fish than it is to animals on the land, since 

 scent permeates the water more evenly than it does the air. 

 Like the wolves, foxes, and dogs, pursuing fish follow the 

 scent. 



The chemical substance that is the basis of smell is the 

 excreta of fish. In land animals this substance is the secre- 

 tion of the skin and the feet. Since fish have no sweat or oil, 

 only the excreta and the specialized scent glands about the 

 intestinal tract and organic matter from the outside give 

 scent. 



The internal ear of the fish is within the skull, near the 

 brain, giving the appearance of a sounding chamber. With 

 the exception perhaps of monkeys, fish require a more 

 delicate balancing mechanism than mammals. The balanc- 

 ing mechanism or small "stone" lies loose in the chamber 

 of the internal ear in a fish. After removing this stone from 

 the cavity of the ear and replacing it by an exact counter- 



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