Mack Jett Fulwyler, pioneer of flow cytometry and flow sorting (1936-2001).

In any society, professional or otherwise, certain individuals stand out by virtue of their ability, leadership qualities, other personal attributes, or combinations thereof. Mack Fulwyler had all of these but somehow even more. His philosophy of life, revealed in the manner with which he dealt with others, reminded one of Henry Thoreau with respect to the grandeur of nature, Thomas Edison with respect to the virtues of persistence and ingenuity, and Walt Whitman with respect to the freedom of thought and spirit. Mack Fulwyler the inventor made fundamental contributions to numerous fields of science and technology, and Mack the individual enriched our lives by being a superb friend and mentor. In this special issue of Cytometry, his colleagues acknowledge their debt and appreciation with scientific contributions closely linked to Mack’s work—in two cases, representing some of his own unpublished investigations—and with personal reminiscences about their interactions with him. We are very thankful for the opportunity to offer a unique tribute to a towering figure in the field of analytical cytometry and hope that this memorial issue will serve as an inspiration to younger students and practicing scientists. In addition, we recognize not only the memory of Mack Fulwyler but also the living presence of his wife, Carol, unflagging partner through the many successes and vicissitudes that marked Mack’s career.