  Features of particle emission and critical point behavior are investigated as
functions of the isospin of disassembling sources and temperature at a moderate
freeze-out density for medium-size Xe isotopes in the framework of isospin
dependent lattice gas model. Multiplicities of emitted light particles,
isotopic and isobaric ratios of light particles show the strong dependence on
the isospin of the dissociation source, but double ratios of light isotope
pairs and the critical temperature determined by the extreme values of some
critical observables are insensitive to the isospin of the systems. Values of
the power law parameter of cluster mass distribution, mean multiplicity of
intermediate mass fragments ($IMF$), information entropy ($H$) and Campi's
second moment ($S_2$) also show a minor dependence on the isospin of Xe
isotopes at the critical point. In addition, the slopes of the average
multiplicites of the neutrons ($N_n$), protons ($N_p$), charged particles
($N_{CP}$), and IMFs ($N_{imf}$), slopes of the largest fragment mass number
($A_{max}$), and the excitation energy per nucleon of the disassembling source
($E^*/A$) to temperature are investigated as well as variances of the
distributions of $N_n$, $N_p$, $N_{CP}$, $N_{IMF}$, $A_{max}$ and $E^*/A$. It
is found that they can be taken as additional judgements to the critical
phenomena.
