102 l.l . .. H BURB ^ K 



a few weeks before the uhiaI time; wliereby their 

 lives would have been stved. 



Whoever iinderttandt the force of hereditary 

 imtinct will realiie that fuch a departure aa this 

 was for the birds impossible. 



The instinct of migratioD comes to the oiartin:i 

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

 early August. The habit of migration in no more 

 determined by any conscious judgmt the 



bird than is the habit of spring growth lieter- 

 mined by a conscious judgment of the rhubarb. 



The force of untold generations of anoestors 

 impelled the martins to remain where they were, 

 even though starvation was the penalty. 



Wings they had* with which they might have 

 ■ought 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 



