In the last third of Arrowsmith, Terry Wickett is introduced as an annoying but excellent chemist under Gottlieb in McGurk Institute. “Red-headed, rough-faced, and wiry,” he jars Martin Arrowsmith in the beginning with his “rude and slangy” talk, his dissatisfaction with superiors and with the way the Institute is run, and his critical attitude toward Martin himself. Later, Gottlieb, Wickett, and Dr. Nicholas Yeo form a faction with which Martin becomes allied. As Angus Duer had earlier made Martin aware of his ignorance of languages, literature, art and music, so did Gottlieb and Wickett cause him to study mathematics, including trigonometry, analytic geometry, and calculus. He also reads the classics of physical science. During World War I, Terry joins the artillery and sails for France.

It is not until after the Armistice that Terry returns and that he and Martin are again in conflict, this time over the phage. Martin’s return home from St. Hubert, however, brings the two together again, and old enmities are forgotten as Martin joins Terry at Birdies’ Rest to spend fourteen hours a day in laboratory research, leaving the comforts and wealth of civilized society “to scorn delights and live laborious days.” Thus the thorough scientist, Terry Wickett, finds independence and maturity with his kindred spirit, Martin Arrowsmith.