LUTHER BURBANK 
Sir Almroth Wright’s inoculation for the preven- 
tion of typhoid fever. It is at least within the pos- 
sibilities that a not dissimilar inoculation may give 
the tree immunity by developing its powers of re- 
sistance, quite as the human subject is given 
immunity. 
Of course the tree has no arterial system that 
can be inoculated with hypodermic syringe as the 
human subject is inoculated. But the life of the 
tree is dependent on the circulation of fluids with- 
in its tissues none the less. These fluids are taken 
in by the roots, and they find their way to the ut- 
termost leaf. So it is conceivable that by proper 
treatment of the soil about the tree, the tissues of 
the tree itself might be so altered as to become 
resistant to the attacks of the bacterial enemies. 
IMMUNITY THROUGH TREATMENT AND BREEDING 
Nor is this idea altogether theoretical. Experi- 
ments have already been made that look to the 
checking of the growth of the tree by withholding 
fertilizers and water, that the development of the 
tender buds and shoots, which are the usual points 
of attack of the enemy, may be made to take place 
slowly and thus to present tissue of a less succu- 
lent order. 
Such hardening of the wood by withholding 
water has proved effective in the case of some pear 
orchards in Colorado, where it appears that the 
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