32 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4TH Ser. 
SUMMARY OF CONCLUSIONS 
It is maintained: 
1. That bird migration had its origin in the evolution of 
the seasons, and that it is now the adjustment of the bird popu- 
lation of the world to the seasons. 
2. That a large part of migration occurs independently of 
an immediate failure of food; that inheritance involves at most 
an innate desire for travel; that the young learn to migrate 
through the example of the adults; that the adults are guided 
by physical phenomena over areas that experience has ren- 
dered familiar; that migration in its finality becomes in each 
bird an impelling habit: therefore, a bird that has passed the 
stage of dependency migrates because it was born of a race of 
migrants, and has followed the example of its elders until 
migration has become second nature. 
In short, it is contended that the causes of bird migration are 
ascertainable facts and not impenetrable mysteries lying be- 
yond the domain of scientific enquiry. 
