In the making of this book I have incurred many social debts. Gifts, solicited and unsolicited, in the form of advice, information and criticism have been received from a large number of people and organizations in many countries. A list of those who have helped with technical and statistical data is included in Appendix 7. I am grateful to them all for giving so freely of their time and knowledge.

In particular, I wish to record my special thanks to the following for much helpful comment and encouragement sustained over a period of years. Dr W. d’A. Maycock of the Lister Institute; the staff at the Department of Health and Social Security; the Director and staff of the Regional Transfusion Centres at Sutton, Birmingham and Manchester; Professor J.N. Morris of the Medial Research Council, London School of Hygiene and Tropical Medicine; Mr Michael J. Reddin, Miss Sarah West, and Mr John Beddington (who also acted for periods as my research assistants); Dr B. Gullbring of the Karolinska Hospital, Stockholm; Dr Z.S. Hantchef, International Red Cross, Geneva; Dr A. Kellner, New York Blood Center; Dr R. Czajkowski, late of King County Central Blood Bank, Seattle; Dr J.M. Stengle, National Blood Resource program, National Institutes of Health, Bethesda; Professor J.N.P. Davies, Albany Medical College, New York; Professor and Dr R. Stevens, Yale University; Professor Brian Abel-Smith, London School of Economics; Mr Charles Furth of George Allen & Unwin Ltd., London, and Dr Ida Merriam, Social Security Administration, Department of Health, Education, and Welfare, Washington.

To all those who completed questionnaires – and especially 3821 unknown blood donors in England – I also wish to express my gratitude. From their contributions I have learnt so much.

Grants from the Nuffield Foundation Small Grant Program, the Department of Health and Social Security, the Social research Division of the London School of Economics and the Joseph Rowntree Memorial Trust assisted me at various stages to undertake certain studies of blood donors and to analyse a mass of statistical and documentary material. Without such financial help, in all a total of £3250, there would have been gaps in this book.