PLANTS IN THEIR RELATION TO DISEASE. 71 



tissues and cells of the wood. Tliut would seem to me to be 

 the apparent cause often. Sometimes I see it on the south 

 side of a tree, Avliorc the extreme heat of the sun's rays would 

 he brought to bear, and sometimes I see it on the north side 

 of a tree, where the tree is subjected to extreme cold and 

 extreme changes of temperature between day and niglit. It 

 does seem to me that by some cause, whether of heat or 

 cold, the cells of the wood have become ruptured, and thus 

 the free flow of the sap obstructed, which causes this blight. 

 Now for the remedy. AYe see the blight after it is estab- 

 lished ; we do not discover it until the leaves begin to turn 

 black, and then, if we cut around the bark of the tree, we 

 find that the trouble is on the inside, that the flow of the sap 

 is obstructed, and consequently the limb dies. The best 

 course to pursue is to remove the limb immediately, and 

 when it is removed, it has precisely the appearance that a 

 limb will have if you cut it ofi" and put it into your stove 

 oven and bring it to a pretty high degree of temperature. 

 You may call it fungus or you may call it anything else, 

 still we are dealing with something mysterious ; but I do 

 believe that very high cultivation in a pear orchard is con- 

 ducive to pear blight. I know that rows of small trees in a 

 iiursery, in rich spots, where the wash comes down from the 

 surrounding land, are more liable to blight than they are on 

 soil which is not so rich. 



Adjourned to evening. 



Evening Session. 



The Board met at seven and a half o'clock, Mr. Wheeler 

 in the chair, who introduced the lecturer of the evening, Hon. 

 James S. Grinnell, of Greenfield, as follows: — 



You will have the pleasure of listening this evening to 

 one of the only two surviving members of the Board of 

 Agriculture at the date of its organization, some thirty-two 

 years since, who will tell you something of the hindrances 

 to successful farming. I have the pleasure of introducing 

 the Hon. James S. Grinnell, of Greenfield. 



