Mass vs. size diagram (panel a) and mass distribution (panel b) for the 256 clumps detected in the NGC 2264 cloud. Gravitationally bound and unbound clumps, with α_BE < 2 and α_BE ≥ 2, respectively are located with red (resp. blue) markers (panel a) and sum up in a red (resp. blue) histogram (panel b). Panel a: the critical Bonnor-Ebert sphere model (α_BE = 2) at the median clump temperature, T_dust = 13.9 K, is plotted asa black solid line. The physical size of the beam at a distance of 723 pc is plotted as a vertical doted line. Panel b: theglobal 90% completeness level is indicated with a doted line.