LUTHER BURBANK 



given time of year regardless of climatic condi- 

 tions; but they had also given it an equally 

 powerful tendency to respond to the stimulus of 

 cold weather, and to become productive not 

 merely in the season of winter but under the 

 climatic conditions of winter. 



In other words, the combined influences of 

 heredity and of immediate environment were here 

 as always influential in determining the condi- 

 tions of plant growth. 



But, whereas in New Zealand the environment 

 of winter — characterized by cold temperature — 

 coincided with the calendar months of June, July, 

 and August, in the new environment of Cali- 

 fornia the conditions of winter were shifted to 

 the calendar months of December, January, and 

 February. So the two instincts, one calling for 

 productivity in June, July and August, and the 

 other for productivity during cold weather, were 

 now no longer coincident, but made themselves 

 manifest at widely separated seasons, thus pro- 

 ducing a perpetual rhubarb. 



So the net result was that, merely through the 

 retention of old instinctive habits under the trans- 

 formed conditions imposed by migration to the 

 Northern Hemisphere, the winter-bearing rhubarb 

 of New Zealand was transformed, by most careful 

 and persistent selection, into a summer- and 



[180] 



