This book contains two personal reminiscences of historical importance to research on stress and infectious disease. It deals with perspectives on immunity, aging, and disease and the prospects for immunorestoration in the treatment of immunodeficiency arising from aging and stress.

E. L. Cooper In Volume 23 we considered, in seven chapters, the basic armamentarium of the invertebrate immune system and its cells, as well as an analysis of antigens, setting the stage for the initiation of an immune response. We studied cell products, natural or induced, as revealed by nonspecific and specific responses following antigenic challenge such as the pro phenol oxidase system, the lytic responses, the Ig superfamily, and the place this family offers invertebrates and insect hemolymph proteins as candidates for membership. At this point, these various topics seemed to converge, almost to overlap, in some instances, presenting a challenge as to how to move from one subject to another. Chapter 1, in this volume offers the bridge to Volume 23 and its final Chapter 7. This Volume 24 contains contributions pertaining to cell activities and the environment. Chapters 1-4 refer specifically to interactions between cells and the integration of cell activities. The focus is on a functional immune system, with antigenic challenge as a subtopic. In Chapters 5-7, the environment is considered from several points of view and the main subtopic here is the result of the consequences of connections and missed signals. The internal and external environments are treated, revealing what may happen when normal immune responses are interfered with. All this is integrated by the consideration of the three great regulatory systems, the ever-present network that somehow acts as the monitor or control for all incoming and outgoing signals.

E. L. Cooper The Immunodefense System Because invertebrates are exceedingly diverse and numerous, estimates reveal nearly 2 million species classified in more than 20 phyla from unicellular organisms up to the complex, multicellular protostomes and deuterostomes. It is not surprising to find less diverse defense/immune responses whose effector mechanisms remain to be completely elucidated. Of course, I am not advocating that the few of us devoted to analyzing invertebrate immunity attempt the Herculean task of examining all these species to uncover some kind of unique response As these two volumes will reveal, we are doing fairly well in examining in depth only the most miniscule examples of invertebrates, some of which have great effects on human populations such as edible crustaceans or insect pests. This is in striking contrast to the mass of information on the mammalian immune response which has been derived essentially from the mouse, a member of one phylum, Vertebrata, an approach, reductionist to be sure, but one that has served well both the technological and conceptual advances of immunology as a disci pline. The essential framework of immunology, the overwhelming burst of results since the 1960s, have emanated primarily from this single animal. We should not forget the thymus and the bird's bursa of Fabricius, without which we might have been slower to recognize the bipartite T /B system."