“…Donohue, Reiff, Hanson, Betson, and Finch (12) observed cell-free radioactivity in the suspension preparations, and since they ascribed this radioactivity to red cell destruction they inserted an appropriate correction in their calculations of cell numbers. (10) cell suspension Harrison (11) 59Fe-dilution, 3.0 § cell suspension Present report 59Fe-dilution, Harrison (11) on the other hand, contended that the cell-free radioactivity represented loss of cytoplasm but not of nuclei from red cell precursors; he, therefore, made no such correction. There is no loss of cytoplasm when tissue is sectioned; thus, the close agreement of our data with those obtained by Harrison supports his contention (Table VII).…”