Sir William Osier, affirming a prevalent medical bias, once suggested, ""There are three classes of human beings: men, women, and women physicians."" Dr. Alison Merrill, one of the latter, chose surgery as her specialty despite its traditions as an all-male preserve. Author Wrenn documents many of Merrill's training experiences--long hours, short meals, and periodic challenges from patients, nurses, and other doctors. Neither libber nor lump, she never makes sex an issue and reacts coolly to provocative remarks. Moving from cardiovascular surgery through other rotations, she learns to do specific surgical procedures, appreciate experienced nurses, and impart recently acquired techniques to medical students, well enough to make it one step up the hospital pyramid but not through the entire competitive five-year program--she completes her training at another hospital. Married to a Westinghouse engineer who seems a bit of a cipher, she rarely gets home at promised times and always values his willingness to share household chores. As a record of residency, this lacks the sense of urgency and helpful demystification that distinguished Nolen's The Making of a Surgeon, and its dry, uninflected tone never conveys more than the surface elements of her personality or the hospital scene.