1. Faulkner, L. W., Levy, R. P., and Leonards, J. R. (1961). Clin. Cheyn., 7, 637.
2. Welshman, S. G., Bell, J. F., and McKee, G. (1966). J. clin. Path., 19, 510.
3. Low, B. (1955). Vox Sang, 5, 94.
4. Gilbey, B. E., and Lindars, J. M. (1962). J. clin. Path., 15, 47.
5. Surrey The irregular distribution of pathogens within a single specimen of sputum from patients with chronic bronchitis was first demonstrated by May (1953), who found that a true assessment of the bacterial flora was obtained only after multiple cultures. The liquefaction of the sputum using a 1 % pancreatin solution in saline buffered at pH 7-6 and at 37°C was introduced by Rawlins (1953) to overcome the need for multiple cultures, but this technique suffered from the disadvantage that some sticky specimens were slow to liquefy. Other workers (Mead and Woodhams, 1964; Woodhams and Mead, 1965) used N-acetyl-l-cysteine (N. A. C.) as a liquefying agent which they claimed gave a higher rate of isolation of H. influenzae and was more rapid in its action than pancreatin;the Bacteriological Department, G.A.R.A.W.L.I.N.S.From; Hospital, Mayday; Heath, Thornton