LUTHER BURBANK 
fertility even when subjected to freezing tempera- 
ture; being able to live even through snow storms, 
in contrast to the apricot blossoms which wither 
under influence of the lightest frost. 
But no elaborate studies have been made to 
determine whether this difference is associated 
with anatomical differences of structure, the 
knowledge of which might guide the plant 
developer. 
That such differences really exist is suggested 
by the observed fact that the leaves of very hardy 
varieties of apples, for example those grown in 
Siberia, have exceptionally deep layers of epi- 
dermal cells to give protection to the less hardy 
cells that make up the bu’k of the leaf. Possibly 
some similar modification of the cells may ac- 
count for the resistant quality of blossoms that 
are observed to be able to withstand frost. 
THE Microscope May HELP 
If such is really the case, the microscopist might 
come to the aid of the practical fruit grower, 
pointing out to him the particular trees in his 
orchard that tend to produce flowers having their 
structure thus favorably modified. 
This method of selection would have obvious 
advantages over the method of planting trees at 
random in the colder regions, and waiting the 
selective influence of frost. 
[252] 
