The Development of Immunological Capacity in Phylogenetic Perspective

THE LYMPHOID SYSTEM and immunological functions are in their complete construction, late developments in phylogeny. Similarly, the development of immunologic capacities, the construction of full immunologic vigor, and the development of the normal structure of the lymphoid system are late developments in ontogeny. The lymphoid system of mature mammals and man comprises an extraordinarily complex group of cells, organs, and tissues which has been difficult to understand by direct inquiry based on classical, morphological, and experimental approaches. It is for this reason that our group in Minneapolis has been attempting to gain understanding of the relations between structure and function from inquiry which focuses from three separate directions. We have been making an intensive study of the development of the lymphoid system and immunological functions in phylogenetic as well as ontogenetic perspective and have tried to provide a focus for these analyses from the study of developmental and acquired