In this section of the novel, Holden writes a descriptive essay for Stradlater about Allie Caulfield's baseball glove.
Holden's nostalgia for Allie is made clear in this chapter and we see his positive willingness to ruminate on his younger brother, though Allie is no longer alive.
He has no real contact with Allie because he is dead. Allie is a memory.
Writing and thinking about Allie is a way for Holden to maintain a connection to Allie and the innocence he symbolizes in the novel.
The mit is covered in poetry. Allie played in the outfield and he was a dreamy kid. He didn't have much to do in the outfield and he was not completely dedicated to the game, so he wrote poetry on his baseball glove and read it to occupy himself during games.
Allie was a very bright person, according to Holden, and this glove stands as an example of Allie's personality, his intellect, and his charm. Where Allie was pure and innocent and uncompromised, Holden's older brother stands as the opposite.
He mourns the death of his younger brother Allie and regrets that his older brother D. B. is "prostituting" his talent as a writer out in Hollywood.
We see in Holden's tribute to Allie and his baseball glove clear evidence of Holden's preference for childhood innocence over adult maturity.