LUTHER BURBANK 
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 
different 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-pollenized 
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 mark- 
edly from either parent that no one could con- 
found it with either, and that excelled both in the 
capacity for rapid growth so conspicuously as to 
seem to belong not merely to a different species 
but to an entirely different tribe of trees. 
[162] 
