Prior to 1955-56, the function of the avian and mammalian thymus and avian bursa of Fabricius was still an enigma. At this time, we revealed that removal of the bursa would reduce or eliminate future antibody production (Glick et al., 1956). Other investigators confirmed and extended this work to include that the mammalian and avian thymus control cellmediated immunity (Warner, 1967). There is evidence at the moment to suggest that a bursa equivalent in the form of Peyer's patch type of tissue exists in mammals (Cooper et al., 1968; Perey et al., 1968). The ontogeny of antibodymediated and cell-mediated immunities appears to be similar in birds and mammals. Work with the chicken's bursa has contributed immeasurably to our understanding of the immune response. It has supplied investigators both in the agricultural and medical fields with a tool by which they are able to study immunological processes. The impact of the bursa research on immunology is apparent; however, less apparent is its influence on the development of a research program. In the book, Through the Alimentary Canal with Gun and Camera, Chappell (1958) takes the reader on a fascinating trip into the alimentary canal where he and his crew fish for phagocytes and witness for the first time the dance of the hemoglobin molecule. Research in our laboratory, unlike that of Chappell's trip down the alimentary canal, has begun at the other end of the alimentary canal-some will call this the wrong end-where we have studied the bursa of Fabricius. Our bursa research has taken us into the fields of hematology, immunology, and neuroendocrinology. The bursa was first described by Hieronymus Fabricius (Adelmann, 1967). He was a great teacher of his day and, like many teachers today, was surpassed