Sentence:  “I don't mean all of your friends—only a small <WSD>proportion</WSD>—which, however, connects your circle with that deadly, idle, brainless bunch—the insolent chatterers at the opera, the gorged dowagers, the worn-out, passionless men, the enervated matrons of the summer capital,nb...!” 
Meaning of the word marked with <WSD> tags:  A quantity of something that is part of the whole amount or number.