  The meson spectrum of QCD is studied in the framework of nonperturbative QCD
as a function of varying quark masses $m_q$. It is shown, that the total
spectrum consists of two branches: 1) the standard one, which may be called the
flux-tube spectrum, depending approximately linearly on $m_q$ and 2) the chiral
symmetry breaking (CSB) spectrum for pseudoscalar flavor nonsinglet (PS)
mesons, with mass dependence $\sqrt{m_q}$. The formalism for PS mesons is
derived from the QCD Lagrangian with $m_q$ corrections, and a unified form of
the PS propagator was derived. It is shown, that the CSB branch of PS mesons
joins to the flux-tube branch at around $m_q=200$ MeV. All these results are in
close correspondence with recent numerical data on large lattices.
