We have studied the surface morphological instabilities of CBr4 crystals during growth from vapors.We have found that the crystal-growth morphologies depend not only on temperature and supersaturation, but also sensitively on the total pressure of inert gas in the vapor. With increasing inert gas pressure, at otherwise the same growth conditions, crystals with initially smooth surfaces first develop cellular patterns and then evolve into dendritic structures. Although these cellulars and dendrites bear morphological similarity with those found in melt and solution-growth experiments {i. e. , the product 8' R =const, with 8' being either the width of a cellular or the radius of a dendritic tip, and R the growth rate at the corresponding solid front) the destabilizing mechanism appears to be more complex than that from bulk nutrient diffusion. We have found that the surface diffusion on the substrate also plays an important role in surface morphological instabilities in vapor crystal growth. Fig. 1 show crystal morphological evolution with increasing total pressure. Since the vapor pressure of CBr4 at the current experiment temperature range is (only a few torrs [14]) much less than that of the inert gas pressure, the total pressure is actually the pressure of the inert gas. At a total pressure of P=12 torr, a smooth and round crystal surface is observed [ Fig. 1(a)]. (Note that the white Qat area at the center of the crystal is not a facet, it results from setting the microscope out of focus. )However, as the total pressure increases to P=80 torr