30 LUTHER BURBANK 



much as they are fixed forms of plants that vary 

 very widely from the parent forms. 



In a single row I have seedling walnut trees 

 two inches high that are of the same age with 

 others six feet in height, both grown from seeds 

 of the same tree, and under exactly the same con- 

 ditions and this difference continues through the 

 life of the trees. The Shasta daisy and the white 

 blackberry are mutants in the same sense. And 

 as the reader will discover in due course, the list 

 of such anomalies might be extended to tire- 

 some lengths. 



In a word, it is perhaps not too much to say 

 that my entire work has consisted in dealing with 

 mutations in plant life. My chief work might be 

 held, and I believe justly held, to be an exposi- 

 tion of the truth of the theory of mutation in so 

 , far as it applies to the explanation of the origin 

 of species. 



Over and over again, many thousand times in 

 the aggregate, I have selected mutants among my 

 plants and have developed from them new fixed 

 races. But in the vast majority of cases I knew 

 precisely how and why these mutants originated. 



They were hybrids; and they were mutants 

 because they were hybrids. 



And so from the outset I have believed that 

 Professor de Vries's celebrated evening prim- 



