Conclusion

A historian of science brought up on Thomas Kuhn’s concepts of paradigm change and discontinuity in science would probably want to ask whether the clonal selection theory and the massive expansion of the field that followed its acceptance could qualify as the kind of gestalt shift that Kuhn had in mind.

The work on vaccines lost nothing in the transi­tion, although some of it has been less generally useful since the coming of antibiotics. In some cases, it was the very success of the vaccination program that made its continuation unnecessary. In others, such as that of diphtheria, the rarity of the disease in the West has made the serum treatment a thing of the past, though diphtheria is still an important concern of the Haffkine Institute in India. Serologi­cal tests for disease are as important as they ever were.

One of the most significant continuities has been in blood grouping. As well as being directly utilized in hospital blood banking, the thinking about and techniques of blood group serology laid the concep­tual foundation for human genetics in general. Blood group genetics with its complex antigens and its mathematical Mendelism provided a model on which human genetics, and the genetics of proteins and cells, could be patterned.

On the theoretical side, Landsteiner’s work on the nature of specificity is probably more significant now than it was to most of his contemporaries, who were more interested in the control of infectious disease.

The elevated position of Ehrlich’s theory in con­temporary immunology is rather paradoxical. On the one hand, its basic premises of perfect one-to-one specificity of antigen and antibody and firm chemi­cal union of the covalent type had already been out­grown by his contemporaries. His diagrams, like his terminology, seemed to pretend to a concrete knowl­edge that he did not really possess. In addition, the side-chain theory needed a huge diversity of pre­formed antibody specificities. It was this weakness that Haurowitz’s instruction theory of antibody for­mation was meant to correct. But to our contempo­raries, that was just the feature that gave Ehrlich’s theory its lasting value: It was a selection theory, like the theories of the 1950s. Finally, Ehrlich’s drawings of the side-chain theory are a visual meta­phor; they can represent a modern receptor as well as they did the receptor of 1900. Thus, Ehrlich has been given the role of an inspired precursor by his­torically conscious immunologists of the 1980s (Ada and Nossal 1987).

Finally, as Bumet himself saw, the conception of the clone originates in bacteriology, and that of selec­tion, in a Darwinistic population genetics. The theory was not a new one. Instead, it was an old one trans­posed to a new and fertile setting, where it developed a truly explosive heuristic power. Rather than being revolutionary, it placed immunology among the bio­logical sciences of the twentieth century, sharing with them their most fundamental assumptions.

The history of immunology, in spite of its seeming discontinuities, is one of the evolution of a single species: There are few extinctions in the fossil record of this science. But then, it is only 100 years old.

Pauline M. H. Mazumdar