"the piston rods of his machinery of expression..."See in text(Hands)
A metaphor that compares Wing's fingers to the pistons in an engine, like the engine in a car. Pistons make the other parts of an engine move. The comparison suggests that Wing can express himself when he can move his fingers freely. Wing's hands set his "machinery of expression" into motion.
"she was like one who has discovered the sweetness of the twisted apples, she could not get her mind fixed again upon the round perfect fruit that is eaten in the city apartments..."See in text(Paper Pills)
The passage brings the simile of the apples back into the story. Dr. Reefy is equated with the "twisted" (unattractive) apples that are not picked but are actually the sweetest. "Round perfect fruit" can be interpreted as a metaphor for suitors who are attractive and appear to be desirable.
