Well, speaking of death, we've got one more base to cover. Holden digresses in Chapter Twenty-Two about James Castle, a classmate of his that killed himself at Elkton Hills. On the surface, this is another instance where death has come close to Holden – he hears the body hit the ground, he sees the "teeth and blood" all over the place afterwards, and the boy is wearing Holden's turtleneck sweater at the time. That'll make mortality really hit home, especially for someone in Holden's shoes (that is, someone who lost a brother at such a young age).
But the James Castle incident is far more interesting because of the Mr. Antolini connection. During his conversation with/lecture to Holden, Mr. Antolini makes a big deal (he even writes down a favorite quotation) out of warning his former student not to die nobly for an unworthy cause. OK, but what does this have to do with James? Check out the passage where Holden explains his death. It seems that James insulted a (deserving) guy by calling him conceited, and instead of taking it back when threatened and/or abused, he jumped out the window. Sounds like he died nobly for an unworthy cause – exactly what Holden has to be careful not to do.
Also, J.D. Salinger helped us out by explicitly connecting James Castle with Mr. Antolini, since Mr. Antolini is the one to carry the dead body away?