  Cosmological perturbations in the (1+3+6)-dimensional space-times including
photon gas without viscous processes are studied on the basis of Abbott et
al.'s formalism. Space-times consist of the outer space (the 3-dimensional
expanding section) and the inner space (the 6-dimensional section). The inner
space expands initially and contracts later. Abbott et al. derived only
power-type solutions in the small wave-number limit which appear at the final
stage of the space-times. In this paper, we derive not only small wave-number
solutions, but also large wave-number solutions. It is found that the latter
solutions depend on the two wave-numbers k_r and k_R (which are defined in the
outer and inner spaces, respectively), and that the k_r-dependent and
k_R-dependent parts dominate the total perturbations when (k_r/r(t))/(k_R/R(t))
>> 1 or << 1, respectively, where r(t) and R(t) are the scale-factors in the
outer and inner spaces. By comparing the behaviors of these perturbations,
moreover, changes in the spectrum of perturbations in the outer space with time
are discussed.
