I would like to thank the following for advice, assistance, and material help: Mr S. B. Barnes, Dr A. P. M. Coxon, Dr D. O. Edge, and Dr T. R. Elsdale of the University of Edinburgh; Mr D. French, of Lanchester Polytechnic; Dr M. J. Mulkay of the University of Cambridge; Dr N. C. Mullins, of Indiana University. I would also like to thank those crystallographers and molecular biologists who consented to be interviewed, and those who read early drafts of this paper. The research was supported by a grant from the SSRC, and was carried out at the Science Studies Unit, University of Edinburgh, and the Department of Sociology, University of Manchester.