"maples are such sociable trees, said Anne; they are always rustling and whispering to you,"
This is the second time she has mentioned the trees whispering.
"excruciatingly" Not a good idea to hurt Anne's feelings excruciatingly.
"It is possible the matter might have blown over without more excruciation if nothing else had happened. But when things begin to happen they are apt to keep on." How true.
"You harrow up my very soul." What?
"tremenjusly" There it is again.
All I can say is. Poor Gilbert Blythe.
ebullition - the act or process of boiling up
ostentatiously - intended to attract notice
harrow - to disturb keenly or painfully