This section of the book both focused on the emergence and use of the blood test and summed up the major trends cited in earlier chapters with chapter 8. Chapters 6 and 7 first described how the blood count emerged and evolved, then cited the 3 diseases that it was especially used for: pneumonia, typhoid, and appendicitis. The chapters also dealt with the timespan it took for the blood count to be regularly used.
Howell cited the frequencies that each test was given at the Philadelphia and the New York hospitals. He mentioned that the inconsistent implementation of the blood test was due to doctors' personal preference their diagnosis. Many doctors felt they could evaluate blood with the naked eye better than they could by counting through a microscope. This point culminated in the description of the debate between hematologist John Da Costa and Surgeon John Deaver. Da Costa advocated new school lab diagnosis while Deaver felt his intuitive diagnostic skills could only be impeded by time taxing lab tests.
Although Dr. Deaver's point of view may produce some questions about physicians egos it also suggests that many of the costly test done in our present healthcare system are arbitrary and unneeded. Howell further supports this by stating the New York hospital, in progressive era style, tested for everything regardless of the condition by using a standardized form. Howell concludes the book on this note by stating the most important technology in hospitals today are still the ones with communicating and business purposes.