244 GENERAL ZOOLOGY 



king salmon on the Pacific Coast of America spawns in 

 November, at the age of four years and when of an average 

 weight of twenty-two pounds. It spends the whole of the 

 preceding summer in ascending the rivers, taking no food 

 during that time, but living on its stores of fat. The salmon 

 that run up the Columbia River travel a thousand miles, 

 and those in the Yukon journey twice as far. Eggs are 

 deposited on the gravelly bottoms of mountain streams >and 

 the fish ^which have made the long journey die soon after. 

 The young salmon spends more than a year in fresh water 

 before passing down to the ocean to mature. The true 

 eels reverse the condition found in the salmon, passing their 

 adult life in fresh or brackish water and returning to the 

 ocean to breed. 



The behavior of fishes shows great diversity in instincts 

 and in the use of particular sense organs. Many species 

 depend largely on their senses of taste or smell for procuring 

 food, others use their eyes exclusively^ and are quick to 

 take any small moving object into their mouths. Carp, 

 mud minnows, trout and other fishes have been taught to 

 come to a certain spot to be fed, and will respond to signals, 

 such as the ringing of bells or the display of objects of cer- 

 tain colors. Instincts and specialized adaptations are 

 many, modification of behavior is often easy, but there is 

 little or no power of reason. 



Early zoologists assumed that, because fishes live in water 

 where all chemical substances that could be smelled or 

 tasted would be dissolved, there could be no sharp distinc- 

 tion between taste and smell, and some went so far as to 

 affirm that fishes could not smell at all. ' Professor Parker 

 has ^demonstrated,, however, that fishes smell very dilute 

 solutionsan the nasal pits, and taste stronger concentrations 

 with the lips, barbels, or other parts of the body. They 

 therefore show the same differentiation in the chemical 

 senses as that in terrestrial vertebrates, smell being used for 

 perceiving greatly diluted substances and taste for stronger 

 solutions. - 



