102 LUTHER BURBANK 



Materials for Selection 



And it may well be questioned whether this 

 point of view would have been altered even to 

 this day had it not been for a conspicuous and 

 notable demonstration of the possibility of modi- 

 fying existing species of trees. 



The demonstration was made when I took 

 pollen from the flower of a Persian walnut and 

 transferred it to the pistils of the California 

 black walnut. 



Here were two species of trees so notably dif- 

 ferent in form and shape of leaf and fruit and 

 color of wood that not even the most casual 

 observer could confound them. They were not 

 even natives of the same continent, and no 

 botanist would claim that they were as closely 

 related as are many species of forest trees that 

 grow side by side in our woodlands and maintain 

 unchallenged their specific identity. 



Yet when these two trees were cross-pollen- 

 ized they produced fertile nuts, and trees of a 

 new order grew from these fertile seeds. 



The barriers between these not very closely 

 related species were broken down, and a new 

 type of forest tree was produced that differed 

 so markedly from either parent that no one 

 could confound it with either, and that excelled 



