In 1946, when I was starting work as research student under the supervision of Dr F. Sanger, the second edition of Karl Lansteiner's book” The Specificity of Serological Reactions’[I] reached England. In it was summarized the considerable body of information available on the range of antibody specificity and much of it was Landsteiner's own work or by others using his basic technique of preparing antibodies against haptenes and testing their ability to inhibit the precipitation of the antisera and t he conjugated protein. Also described in this book was the work in Uppsala of Tiselius and Pederson in collaboration with Heidelberger and Kabat in which they showed that all rabbit antibodies were in the y globulin fraction of serum proteins and that they had a molecular weight of 150.000. This combination of an apparently infinite range of antibody-combining specificity associated with what appeared to be a nearly homogeneous group of proteins astonished me and indeed still does.