Who is the Professor from the story, Kaddish for a Child Not Born?

During the winter he is imprisoned the narrator meets the Professor, a skinny man, starving from inadequate nutrition and suffering from hard labor, on a carriage transport for the sick. The Professor makes sure the narrator, who is ill and lying down, receives his portion rather than keeping it for himself. This small action saves the narrator's life and probably further jeopardizes the Professor's survival.