  Non-linear susceptibilities upto the eighth order have been constructed in
QCD with 2 flavours of dynamical quarks. Beyond leading order, they exhibit
peaks at the cross over temperature, T_c. By analyzing their behaviour in
detail, we find that the dominant contributions near T_c come from a set of
operators with a remarkably simple topology. Any effective theory of QCD near
T_c must be able to explain these regularities.
