104 THE NEW HORTICULTURE. 



two unsolved problems in this disease are : First, Where do 

 the bacteria of blight come from, in the case, for instance, of 

 isolated pear trees far distant from any known case of blight? 

 I once saw several large LeConte up in the mountains near 

 Eureka Springs, Ark., and miles away from any other pear 

 tree, with large dead blighted limbs in the center of the trees, 

 caused by an attack some years before, but, from neglect on 

 the part of the owner, never cut out. Now, the authorities 

 all affirm that such dead wood is the nidus, or harbor, for the 

 bacteria ; yet there stood those blackened limbs among the 

 other healthy branches, and not a sign of blight that season. 

 Was the whole air filled with blight germs, in the first in- 

 stance? If so, where did they go, and why did the tree not 

 blight again? The second unsolved problem is, what are the 

 conditions most favorable to an attack of blight? 



Now, while our government and other scientists cannot 

 tell us where the bacteria usually come from, they are all 

 agreed that the germs are external to the tree in an original 

 attack, and do come from somewhere. Witness their state- 

 ments that blight spreads, that the tender shoots are most 

 liable to attack, that the bacteria enter the cut ends of shoots, 

 etc. As to the second problem, they tell us nothing. Now, 

 twelve years ago, seeing that the phenomena of blight were 

 inexplicable on the external theory of an attack from the air 

 exclusively, there was but one other possible hypothesis, 

 which is that the bacteria are indigenous to, and in the sap of, 

 every pear and apple tree naturally, in limited numbers, and 

 perhaps, under normal conditions, play a specific, useful part 

 in the life and development of the trees. A contrary supposi- 

 tion demands a belief in an actual creation of this germ a 

 hundred or so years ago, when the disease first appeared in 

 New England. But science denies the possibility of spon- 

 taneous generation or an actual new creation ; consequently, 

 the germs must have been in the trees and developed at that 

 time as a result of certain favorable conditions of temperature, 

 moisture, light and electricity. Therein lies the whole prob- 

 lem of bacterial life. 



To illustrate, suppose a man should raise a window-sash 



