  The magnetic susceptibility and specific heat of the one-dimensional S=1
bilinear-biquadratic Heisenberg model are calculated using the transfer matrix
renormalization group. By comparing the results with the experimental data of
${\rm LiVGe_2O_6}$ measured by Millet et al. (Phys. Rev. Lett. {\bf 83}, 4176
(1999)), we find that the susceptibility data of this material, after
subtracting the impurity contribution, can be quantitatively explained with
this model. The biquadratic exchange interaction in this material is found to
be ferromagnetic, i.e. with a positive coupling constant.
