Comparative pathology of marine invertebrates and the study of human disease.

Studies on an infection with gram-negative bacteria in Limulus led to the 
discovery of the extreme sensitivity of the amebocytes to a gram-negative 
endotoxin. This led to the development of a method for measuring 
very small amounts of endotoxin in biologic fluids and in human 
blood. Yet, had the original observation of Cantacuzene on the large 
common edible spider crab been followed, this remarkable sensitivity of marine 
arthropod blood to endotoxin would have been recognized much earlier. The 
original work of Metchnikoff on sea star larvae stimulated him to 
develop the major theory of phagocytosis but, until the adult animal 
of the same genus was re-examined half a century later, the 
presence of a powerful substance which selectively inhibits growth of lymphocytes 
following primary immunization remained unknown. Though mucus secretion is a fundamental 
characteristic of most invertebrate phyla and all vertebrates, little is known 
about the regulatory mechanism of the secretory process; studies of the 
responses of specialized invertebrate secretory cells to infection have now led 
to a new means of studying macromolecular control of mucus secretion 
in man. These three stories emphasize the continuing need to study 
disease as a biologic phenomenon. 