LUTHER BURBANK 



cite an illustration from another branch of the 

 organic world. 



Take the migrations of birds as a familiar 

 instance. If you watch the birds at all, you have 

 doubtless noted that the migrants that come to 

 temperate regions from the tropics arrive each 

 spring in your neighborhood at a date that you 

 may fix in advance with almost entire certainty. 



The hardier birds, to be sure, such as the robin, 

 the blue-bird, and the meadow-lark, retire before 

 the blasts of winter somewhat unwillingly and 

 they begin their northward migration at a period 

 that may vary by a good many days or even weeks 

 according to the forwardness or backwardness of 

 the season. But the coterie of tender birds — 

 orioles, vireos, wood-robins, tanagers, fly-catchers 

 —which spend the winter in the region of the 

 equator, must begin their northward migration 

 without regard to the climatic conditions, inas- 

 much as their winter home is a region of per- 

 petual summer. 



They start northward merely in obedience to 

 an instinctive time-sense that has been implanted 

 through long generations of heredity, and they 

 move across the zones with such scheduled regu- 

 larity as to reach any given latitude almost on a 

 fixed day year after year. 



In Massachusetts or New York or in Ohio or 



[184] 



