Finite-amplitude convection in the form of rolls and their stability with respect to
infinitesimal disturbances is investigated in the case of boundaries of the horizontal
fluid layer which exhibit a thermal conductivity comparable to that of the fluid. It is
found that even when rolls represent the preferred mode at the onset of convection
a transition to square cells may occur at slightly supercritical Rayleigh numbers.
The phenomenon of inertial convection in low Prandtl number fluids appears to
become more pronounced as the conductivity of the boundaries is reduced. Modulated
convection rolls have also been found as solutions of the problem. But they appear
to be unstable in general. Experimental observations have been made and are found
in general agreement with the theoretical predictions.