Top panel: ratio of the de-reddened Brα and Brγ fluxes of Class II sources shown as a function of L_★ (left), L_acc, computed from the Brγ luminosity (center; see Sect. 3.3), and the extinction in the K band (right). Bottom panel: same but for the ratio of Pf_γ to Br_γ fluxes. The values of the ratios are shown by filled dots; the 3σ upper limits are indicated by arrows. When not visible, the errors are smaller than the dots. In both sets of panels, the mean values of the ratios and their uncertainties are shown in orange.