The equation of the white jacket with Dr Monygham's "concession" suggests a white flag of surrender, of the sort he exhorts to be raised in Chapter 3-10. I.e., Dr Monygham, who distrusts people's motives, has surrendered in this case to an example of "character" worthy of "respect." "Character" is a key recurring word in the novel, signifying the valuable inner soul that is the only redeeming aspect of the otherwise tragic human condition.