20 THE MIGRATION OF BIRDS. 



supposed to migrate by " instinct," knowing not 

 how or why, impelled along a course that never 

 errs or changes, flying from point to point with 

 no more mental effort than a piece of inanimate 

 mechanism, hurrying away as an arrow from a bow, 

 and just as incapable of swerving from their track 

 until their flight is done. Were such a miraculous 

 power really possessed by birds, then of a surety 

 they would be transcendently more endowed with 

 mental attributes than Man, creation's Lord him- 

 self! Ascribing such a faculty to these creatures 

 means on the one hand exalting them to a super- 

 human height of intelligence, or on the other hand 

 degrading them to the passionless depths of mere 

 irresponsible automata. Both courses are as un- 

 necessary as they are unscientific and illogical. 

 Migration is a Habit, and like all other habits has 

 had to be acquired ; it is, however, by no means a 

 universal habit even amongst the individuals of 

 many species ; some migrating, others remaining 

 stationary, according to the exigencies of their sur- 

 roundings. Nay, more, we might almost say that 

 uniformity is the exception rather than the rule. 

 Were migration an inherited instinct, it is only 

 reasonable to presume that it would be transmitted 

 from parent to offspring in one unbroken and 

 unchanging order of descent. 



Let us glance at a few instances. The Robin 

 {^Erithacus rubecula) is a migrant in all the colder 

 portions of its range, where the winters are suffi- 

 ciently severe, passing for instance between Scandi- 



