“…It has been estimated that the normal individual has about 10 CFC per 106 nucleated cells in the peripheral blood (Chervenick and Boggs, 1971) (Moore et al, 1973b Golde, Finley and Cline, 1972;Chervenick and LoBuglio, 1972 The finding that the peripheral blood of untreated patients with CGL does not provide CSF could be explained in a number of ways. In the first place it is possible that CSF is produced but consumed locally by CFC and cluster forming cells present in the feeder layer.…”