LUTHER BURBANK 



(pure recessive) that will also breed absolutely 

 true, and two tall vines (mixed) that will not 

 breed true because they contain factors both of 

 tallness and of shortness. 



The essential truth of the Mendelian formula 

 has been demonstrated by thousands of observa- 

 tions, but a good many workers who have ob- 

 served its application in simple cases have failed 

 to realize the true bearing of the phenomena. The 

 truth seems to be that it is only the comparatively 

 superficial and newly acquired characteristics of 

 any organism that still have sufficient flexibility 

 to be experimented with by nature in this game 

 of chance that we speak of as Mendelian heredity. 



Stated otherwise, what we term Mendelian 

 inheritance appears to be nature's method of test- 

 ing out new qualities that are from time to time 

 impressed on the organism through the influence 

 of environment. 



Some individuals of a certain strain of plants 

 or animals chance to be subjected to influences 

 that modify somewhat the color of flowers, the 

 texture of hair, the size of body, or what not. An 

 individual of this modified race presently inter- 

 breeds with an individual not so modified. 



The important question is this: Is the modi- 

 fication beneficial to the species or otherwise? 



The matter is put to an impartial test through 

 the operation of Mendelian heredity. 



All the immediate offspring present tangibly 

 the modified character, but the unmodified char- 

 acter is given a hearing again the next genera- 



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