Lymphatics, Lymph and Lymphoid Tissue

In the introductory chapter of this book it is explained that in the lower vertebrates there are lymphatic vessels but no lymph nodes; the lymphoid tissue in fish and amphibia is associated with myeloid tissue in such organs as the intestines, kidney, and liver. Lymph nodes first appear in certain birds, but it is only in mammals that they are invariably present. However, even in mammals, where lymph nodes are always associated with lymphatic vessels, no physiological link has yet been established between the functions of lymph and those of lymphoid tissue. The justification for treating these topics together in a single volume is thus largely anatomical. In this new edition of Lymphatics, Lymph and Lymphoid Tissue Dr. Courtice gives a lucid and authoritative account of the formation and properties of lymph. This involves a discussion of recent views on the structure of capillaries and a detailed account of their permeability to the various constituents of plasma. The striking fact emerges that from 50 to 100 per cent of the plasma proteins pass through the capillaries into the extravascu-lar compartment each day to be returned by the lymphatics to the blood. There are chapters on the physiological significance of the regional lym-phatics, including the special role of the intestinal lymphatics in fat absorption , and on conditions involving abnormal function of the lymphatics, notably oedema. At the time of the first edition of this book in 1941 it was generally agreed that lymph nodes performed three functions: they filtered foreign material from the lymph more or less efficiently, they produced antibodies, and they produced lymphocytes. The problem of the fate of the lymphocyte, posed by the daily entrance of large numbers of lymphocytes into the blood, was unsolved; the function of the lymphocyte was unknown. A careful reading of Professor Yoffey's chapters in the present edition shows that the last 15 years have added little of importance to our understanding of the physiology of lymphoid tissue and the lymphocyte, apart, perhaps, from establishing more firmly that lymph nodes produce antibody. A considerable literature has, of course, accumulated in these intervening years and Professor Yoffey has done a useful service in providing a comprehensive account of it. Basic and clinical investigators are now concerning themselves with a critical re-evaluation of many of the old concepts "embalmed" between hard covers of some very old journals, monographs, and treatises. This is certainly an …