What is the purpose, effect of Jefferson's refusal to eat Miss Emmas food?

Jefferson refuses the food Miss Emma has sent him, because such food is for humans, and “I’m a old hog they fattening up to kill for Christmas” (83). Grant replies that he is a man, but Jefferson continues to insist that he is a hog, crawling on the floor and eating out of the bag without using his hands. Grant is irritated by Jefferson’s behavior, but says that he won’t tell Miss Emma because it would break her heart.

The effect of this section is to illustrate Jefferson's inner feelings of who (or what) he is. The words of the lawyer, who described him as a hog, have convinced Jefferson that he is how he was described. In his own eyes, he's not a man.