There is mention of Upton Sinclair on 37 that seems particularly significant to me.  This historical reference relates to the terrible sanitation and food preparation conditions in the city at the time explored in Sinclair’s book The Jungle.  The Union Stock Yards (which would also be the meatpacking district) are described.

The few who found it invigorating tended to be men who waded in its “river of death,” Sinclair’s phrase, and panned from it great fortunes. (p. 38)

By calling upon Sinclair’s descriptions and phrases, we are reminded that this is an historical period where everything is raw and rough.  The childhood incident is also a reference to the survival of the fittest attitude that reigned supreme then.