102 LUTHER BURBANK 



a few weeks before the usual time ; whereby their 

 lives would have been saved. 



Whoever understands the force of hereditary 

 instinct will realize that such a departure as this 

 was for the birds impossible. 



The instinct of migration comes to the martins 

 in September, not in August, or at least not in 

 early August. The habit of migration is no more 

 determined by any conscious judgment of the 

 bird than is the habit of spring growth deter- 

 mined by a conscious judgment of the rhubarb. 



The force of untold generations of ancestors 

 impelled the martins to remain where they were, 

 even though starvation was the penalty. 



Wings they had, with which they might have 

 sought and found a new environment where food 

 was plentiful; but they were powerless to use 

 the wings at this particular season, because the 

 particular week had not arrived at which the 

 hereditary clockwork of their organisms would 

 strike the hour for migration. Taken by the 

 race at large, it is better for the martins that they 

 should not migrate until September; this fact 

 had been established through the test of thou- 

 sands of generations, and the result was regis- 

 tered indelibly in the organism of every bird. 

 Were it possible to destroy the racial tradition 

 in the interests of any single generation, the life 



