Dr. Geison is examining the history of physiology at four leading research schools in the discipline in the United States before World War II: Chicago, Harvard, Johns Hopkins, and Washington University, St. Louis. Despite a rapidly growing body of literature on the history of the biomedical sciences in the United States, the technical and conceptual content of physiology has attracted little attention. Of the four schools he is studying, only Harvard has been examined previously in any detail, and even in that case much remains to be done. This study represents a preliminary phase in a broader study of the social, conceptual, and technical history of American physiology. That larger study seeks to test the hypothesis that one can identify a distinctively "American" (or at least "Anglo- American") style of physiology, characterized by decentralized models of biological control hormones. The initial focus here is physiology at Chicago, partly because the research there carried out by A. J. Carlson seems to run against the grain of this alleged "American style" but also because of an accelerating activity in the history of science at Chicago as that university approaches its centennial celebration in 1992--thus allowing a comparative study of physiology with the other branches of the history of biology being studied there. If this exploratory study works out, a broader research program will be pursued.