After having worked for a while on his own, Gottlieb tells Martin that both he and Terry believe that he needs to learn more mathematics, physics, and chemistry in order to really get to work. This insults Martin's pride, but Terry calms him down and offers to tutor him. It is at this point that a friendship is formed between Martin and Terry.
Meanwhile, America has joined the war, and Tubbs has offered the services of the institute to the War Department. Everyone, except Gottlieb and two others, is made officers and are told to buy uniforms. They will have to play their part in the war and make sera. Wickett actually joins the artillery in France, leaving Gottlieb behind to suffer prejudices because of his German heritage.
Martin feels as though the war is an interruption to his work and yet finds himself attracted to the uniform, at first. He comes to like the salutes and the respect he receives being an "officer," but this novelty soon wears off. In fact, Martin chooses not to wear the uniform when he goes out with Leora but is found out by Holabird who lectures him and mentions his own war wounds. Martin begins to become annoyed by Holabird.
When these Chapters begin, Martin is still at the Rouncefield Clinic, which he does not like. The narrator, the author, and the protagonist agree that the Clinic is a place for one to "succeed," advance monetarily, and achieve notoriety. This is different from the "ideal" of science for which Gottlieb stands and for which Martin so often longs. The Clinic is called a "medical factory," by which Lewis hones in on the commercialism of the medical "business." It is a place where practicality is key, as is seen by Angus's plea to Martin to use his research time for something practical and useful for the clinic. Originality and independent thinkers are looked down upon and thus the phrase "medical factory" takes on the same significance as had the comparison of the University of Winemmac to a mill, they are institutes that churn out self-important clones.
Although Martin seems happy at first at the McGurk Institute, it becomes apparent, little by little, that this institution is not void of the faults that had plagued the clinic. Although Martin has more freedom, there is a call for "co-operation," and there is an emphasis on money, success, and competition as seen through the symbol of the centrifuge. The centrifuge, which Holabird is so proud of, is supposed to be a status symbol because it is an expensive piece of machinery as well as it being the "fastest," which points to the sense of competition that exists in the medical world.
The McGurk institute is supposed to be a double of the real life Rockefeller Institute. In fact, Sinclair Lewis wrote this book because he had met a man named Paul De Kruit who had been unemployed by the Rockefeller Institute for having written a kind of "exposé" of American medicine. Lewis drew from De Kruit's opinions and experiences at the institute and in medicine in general. And from this comes the hierarchical critique of the McGurk Institute and others that came before it in the novel. De Kruit was, of course, a laboratory man, who much like Arrowsmith had come to the conclusion that the laboratory scientists within institutions only existed to bring fame to each institute.