Trout and Salmon 195 



longer theory but fact. Moreover, the word farent is mis- 

 leading. The fish do not necessarily return to the stream of 

 their parents, or even to what might be called their "parent 

 stream." They return to the stream in which they them- 

 selves grew up. Sockeye eggs were brought from Alaska and 

 hatched at Bonneville on the Columbia River. The little 

 fish were marked. They went out to sea, and when they re- 

 turned to spawn, they went not to Alaska but to the Columbia 

 River. They not only entered the Columbia, but they swam 

 up it one hundred miles to Bonneville and there they de- 

 posited their eggs. Their young grew up, were marked, 

 went out to sea, and in due time this second generation 

 also came back to Bonneville to spawn. They had adopted 

 this water as a "foster-parent." 



How are these astounding feats of home-finding accom- 

 plished? This question has several parts, susceptible of dif- 

 ferent answers. In the first place, the fish must find his way 

 through trackless ocean waters to the mouth of his own 

 river. Other animals perform similar voyages: birds fly vast 

 distances between summer and winter quarters, flightless 

 penguins swim with infallible precision from the Antarctic to 

 South America and back, adult eels find their way across the 

 ocean to their breeding grounds near the West Indies. All 

 we can say is that some powerful directional sense is at 

 work, and it may be that there is something in the hypothe- 

 sis that it is the action on the semi-circular canals of the ear 

 and their associated sense-organs of the so-called "Coriolis 

 force" — a resultant of such geo-physical factors as the rota- 

 tion and angular velocity of the earth, the velocity of a body 

 relative to the earth's surface, and the angle between the 

 body's direction of motion and the earth's spin axis. 



Assuming that some such force does exist to keep the 

 salmon on the proper compass course, how does he distin- 

 guish the waters of his own river system from the others with 



