Martin begins his experience as a house physician by treating a factory worker who has been suffocated by smoke in a fire at Boardman Box Factory. The spectacular ride to the scene of disaster in an ambulance and the subsequent treatment of the victim give Martin a feeling of superiority, pushing laboratory and test tubes into the back of his mind.
The first year of his internship, Martin is thrilled by his battle against fire, flood, and disease. The second year, such experiences become routine. He is homesick for the laboratory and "the search for fundamental laws which the scientist . . . exalts above temporary healing." An evening that he and Leora spend as guests of Dean Silva nearly convinces him that the life of a practitioner is preferable to that of a laboratory man, but a chance meeting with Gottlieb and Leora's unbounded praise of the wretched but great man make Martin wonder again about his choice. In the meantime, he finishes his internship and leaves Zenith for Wheatsylvania.
His training finished, Martin Arrowsmith, M.D., is now ready to move on to independence and Wheatsylvania, and to become a full-fledged general practitioner. This transitional chapter also brings Gottlieb back into the story, again in contrast with Silva. With almost incredible insight and understanding, Leora instantly realizes Gottlieb's greatness: "He's like a sword — no, he's like a brain walking!" she tells her husband. "I'd black his shoes!"
The rift is not healed at the time, however, and Martin goes his way to become a square peg in a round hole, a practicing physician in Wheatsylvania.