Under the auspices of the U.S. Public Health Service and the Navy,  Rosenau and his colleagues, in an effort to “determine the mode of  spread of influenza,” tried to infect military volunteers with  Pfeiffer’s bacillus at a makeshift infirmary on Gallops Island in Boston  Harbor. Though human experiments were then seen as acceptable, in a  paper later published in 
JAMA, Rosenau noted that the team “proceeded rather cautiously at first by administering a pure culture” of the bacterium.
  
When the “trials proved negative,” he wrote, “we became bolder.” The  scientists gave each of the volunteers “a very large quantity of a  mixture of thirteen different strains of the Pfeiffer bacillus, some of  them obtained recently from the lungs at necropsy.” They also inoculated  the men with specimens taken from the throats and noses of influenza  patients and later with the patients’ blood. Still no symptoms, so next  the volunteers shook hands with, talked with, and were coughed on by the  actively ill. They remained healthy.