BLIGHT. 121 



well as local attacks on trees, occur from a vastly increased 

 generation of them, brought about by certain favorable con- 

 ditions. Herein lies the whole problem of bacterial life, both 

 in man, trees and everything. It is simply a question in both 

 of conditions. For instance, if yeast be mixed with dough 

 and placed in a temperature below freezing, the mass will not 

 rise; nor if placed at once in a heated stove will it rise. Both 

 are wrong conditions. Now, let scientists find out for us just 

 what are the conditions under which these bacteria multiply 

 so enormously in the sap of trees as to cause the phenomena 

 we call blight, yellows, etc. With a view to aid in solving 

 this problem, I present some observations from my own ex- 

 perience, as well as a few suggestions on the subject. 



There are two main points to be considered : i. Where 

 do the bacteria of blight, for instance, come from? 2. What 

 are the conditions most favorable for their propagation in 

 numbers sufficient to produce the effect called blight ? There 

 are but three possible answers to the first question. Leaving 

 out the one-time accepted theory of spontaneous generation, 

 which science has demonstrated to be false, air sterilized by 

 heat and kept from contact with the atmosphere showing no 

 signs of bacterial life so long as thus excluded, the bacteria 

 of blight come either from the soil, from the air, or they are 

 indigenous to the sap itself, of course in numbers ordinarily 

 harmless. That they are taken up by the tree from the soil 

 has no advocates that I am aware of, the generally accepted 

 theory being that they are strictly external to the tree, and 

 make their attack from the outside. Witness the statement 

 that blight spreads, that the fruit spurs and tender shoots are 

 most liable to attack, and directions to cut back the affected 

 parts. Of course, the latter would do no good if the bacteria 

 were already in the sap of the tree. That they are thus in- 

 digenous to and in the sap of every pear and apple tree now, 

 and always have been, is the only possible hypothesis which 

 will explain all the phenomena of blight. For instance, an 

 apparently healthy pear tree may be planted miles away from 

 any other tree, and yet when the proper conditions arise, 

 which I will presently explain, it will show blight. Are we 



