Mass versus size diagram. Starless and protostellar MDC candidates in NGC 6357 are displayed as blue and red dots respectively. For comparison, following Nony et al. (2018), we also display massive starless and protostellar MDCs (Motte et al. 2007; Tigé et al. 2017; Tan et al. 2013; Louvet et al. 2014) as red crosses and circles respectively, and pre-stellar and protostellar sub-fragments and cores (Motte et al. 2018b; Tan et al. 2013; Bontemps et al. 2010; Louvet et al. 2019)as blue crosses and circles respectively. The red and blue lines represent mass radial power-laws of Mass(<r) ∝ r and Mass(<r) ∝ r².