LUTHER BURBANK 



no organism freed from the struggle for existence; 

 although, of course, under the conditions of 

 civilization the operation of "natural selection" 

 may be modified through man's influence, and the 

 conditions of life for a given organism radically 

 changed by artificial selection. 



Evolution Through Mutation 



But let us not forget our theme. With the 

 case of the scented calla to furnish our text, I 

 was about to speak of those variations from the 

 normal on the part of any given organism which 

 lie outside the ordinary range of variation and 

 which therefore constitute so definite and pro- 

 nounced a departure that they have long been 

 spoken of as "sports." 



To these the present day evolutionist, following 

 Professor Hugo de Vries, gives the name of 

 "mutations." 



It has already been said that the appearance of 

 a scented calla constitutes such a change. But of 

 course the anomalies that are usually listed as 

 mutations are as a rule of an even more noticeable 

 character. A classical illustration was given by 

 Darwin himself in the case of the Ancon ram, 

 which was born with legs only half the normal 

 length, and from the progeny of which was 

 developed a short-legged race of sheep. 



But the word mutation had not come into 



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