'20 \ Phillips, Migratio Ac [ April 



edge of instinctive notions and their causes is doubtful, \\ith 

 the masses of facts being brought constantly to light relative to 

 bird travels, we are perhaps a little apt to lose sight of some of 

 the old time mystery o( the subject. The modern tendency seems 

 to be to sniff at the word ' mystery ' as applied to any phenomenon 

 of bird migration. This is merely a question of where the word is 

 applied; it' to the actual facts, then it is hardly warranted, but 

 if to the causes, then it is certainly as applicable now as ever. 

 Supposing the facts all at hand, what would the student know about 

 the actual inherent impetus, the heritability of instinct, or the 

 powers of orientation and their mechanism! Would he be one 

 whit hotter oil' than the present day systematist who with all his 

 finely cut races does not really know how or why a new species 



arises? 



Mystery there certainly is. and mystery there will always ho 

 as lone as the great biologic problems remain unsolved. The 

 formation ami maintenance o( this time sense is only one of those 

 activities of nature which tend to make the sternest advocate of 



mechanism doubtful of its all-sufficiency. It is so much easier to 

 tind behind that clock-like movement a vital impetus, 'a guiding 

 unity.' 



"It (the evolution of \iiv is a creation that goes on for ever in 

 virtue of an initial movement. This movement constitutes the 

 unity of the organised world a prolific unity, of an infinite 

 richness, superior to am that the intellect could dream o\. for the 

 intellect is only one of i:- aspects or products." [Bergson. 



