Evolution of the mass per unit length of filaments according to the toy gravitational-accretion model described in the text, for five values of the initial line mass at t = 0: M_line(0) = 1 M_⊙ pc⁻¹ (black solid curve), M_line(0)∼8 M_⊙ pc⁻¹ (half critical, black dashed curve), M_line(0)∼16 M_⊙ pc⁻¹ (critical, blue solid curve), M_line(0)∼32 M_⊙ pc⁻¹ (twice critical, blue dashed curve), M_line(0)∼100 M_⊙ pc⁻¹ (highly supercritical, blue dash-dotted curve). The red dotted horizontal line marks the critical line mass of ∼16 M_⊙ pc⁻¹. Time is normalized in such a way that a critical filament with M_line = M_line, crit at has M_line = 4 × M_line, crit at (solid blue curve), corresponding to ∼1−2 Myr.