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2. Bone Marrow Transplantation. P. 178;Pegg, D.E.,1966
3. Zuckerman, A. J., Tsiquaye, K. N., and Fulton, F. (1967). Brit. J. exp. Path., 48, 20.
4. STANDARDS A stock solution of oxyhaemoglobin was made by haemolysing the red cells of pooled heparinized blood with distilled water, the solution then being clarified by centrifugation. Suitable dilutions of this solution were made in phosphate buffer (pH 7 5) to obtain final concentrations of oxyhaemoglobin to cover the range 5-75 mg. per 100 ml. The haemoglobin content was found by making parallel dilutions in a modified Drabkin's solution (Dacie and Lewis, 1963a), and the cyanmethaemoglobin concentration of each dilution was found by reference to a known cyanmethaemoglobin standard solution
5. Received for publication 25 Mav,1967