role centered around work.  This is certainly true in the case of the narrator.  He is unnamed because it is his position, as "the lawyer", that identifies him.  He speaks of nothing outside his work - his concern with Bartleby centers around the fact that Bartleby is his employee.  Nothing is ever mentioned of his home life, family, etc..

Turkey, Gingernut, and Nippers, sharing similar positions, have to be identified by personality traits.  Again, names have lost importance, because names suggest individuality.  These nicknames, which center around how these characters behave at work, are used instead.  Turkey is so known because, as is suggested, he indulges himself too much at lunch, causing his afternooon work to suffer.  Nippers is so named because he is irritable and seems unsatisfied with his position in society.  Gingernut earned his name because off the treat he brings back when he is sent on errands.  Again, for all these characters, no personal life is mentioned.  Melville's theme is that workers in America have no personal life, no individuality - which is what brings Bartleby's downfall in the end. 

One of the themes of the story is the way that society often finds it hard to deal with those who are different. And Bartleby certainly couldn't be more different if he tried. The whole culture of Wall St is based on a certain element of regularity. The demands of commerce dictate an adherence to a specific set of rules and commercial customs designed to facilitate the smooth operation of business.

Then along comes Bartleby who just sits there, doing nothing. Though not actively belligerent, Bartleby still represents a threat to the commercial order which relies on everyone involved fulfilling their specific function. The economic system which Bartleby refuses to serve is based on rampant individualism. Yet ironically his very individuality represents a danger to that system. Society in general, and Wall St in particular, cannot accommodate too great an expression of individuality. Eccentricities can be tolerated, even encouraged in certain cases. But there are limits, and Bartleby, in his passive act of defiance, pushes those limits as far as he possibly can.