Prince. — Why Do Salmon Ascend from the Sea? 137 



Migration Tendency Ineradicable. 



Habit is amazingly tenacious and persistent. It is so strong 

 that it seems to pass to successive generations and reappears 

 with undiminished strength as an ancestral tendency. It is true 

 that the English skylark, which soars to considerable heights 

 when it sings, has lost that habit in New Zealand, and the strange 

 spectacle is offered of the imported, acclimated skylarks singing 

 their wonderful song, while indolently seated on a stone wall or 

 on a wooden fence. On the other hand, the Apteryx or Kiwi, that 

 ancient type of wingless bird which survives only in New Zealand, 

 still tries to hide its head under the paltry stump, the small remain- 

 ing vestige of its wing, when it goes to sleep ; the most curious and 

 pathetic case of persistence of habit known to scientists.* Our 

 dogs before slumbering usually move round and round on the 

 carpet, or even the stone floor, illustrating the survival of their 

 ancestors' habit of smoothing down the coarse stubble or grass 

 in the form or a lair or nest. With regard to Salmon — Inspector 

 W. L. Calderwood, the well-known Scottish authority, in his 

 report (Scott. Fish. Board Report, 1910, p. 7), says, having regard 

 to their surpassing economic importance, it is "fortunate that the 

 Pacific coast species have acquired the habit of entering fresh- 

 water at all;" but this does not accurately represent the case, 

 for these fish merely have adhered to their ancestral habit of 

 seeking the old established spawning grounds. They have never 

 wavered, if the view here set forth be the true one, in making their 

 way to the old resorts, century after century. Topographical and 

 physical changes have left the habit unchanged. Even so strong 

 an advocate of the fresh-water origin of the Salmon as Sir Herbert 

 Maxwell admits that environment has little influence on the 

 migratory fish, and he speaks of "heredity" as determining the 

 lateness or early character of salmon rivers, declaring that "the 

 earliness or lateness of a salmon river depends not so much on the 

 nature of the water, or its channels, as on the hereditary peculiari- 

 ties of the race of fish frequenting it." (Salmon and Sea Trout, 

 1898, p. 226). He refers, in this connection, to the strong impulse 



* The late Professor H. N. Moseley (Oxford) of this example remarked: 

 "How strong is the tendency in birds to preserve their habits. I know of no 

 more striking instance than this. (Notes of a Naturalist on H. M. S. 

 "Challenger.") 



