||Alan S. Perelson, Ge´rard Weisbuch, Immunology for physicists, Rev. Mod. Phys. 69, 1219–1268 (1997) p.1226 left column bottom paragraph
||Du Pasquier L. Ontogeny of the immune response in cold-blooded vertebrates. Curr Top Microbiol Immunol. 1973 61: 37-88. & Du Pasquier, L., and J. Haimovitch, 1976, Immunogenetics 3, 381.PubMed ID4578664
||"...the smallest known immune
system is that of a young tadpole, which is
estimated to have 10^6 lymphocytes and thus a repertoire
of order 10^5 to 10^6 (primary sources)."