  We present SMA interferometric observations of the 12CO J=2-1, 13CO (J=2-1),
and C18O (J=2-1) lines and 225 GHz continuum emission and SMT single-dish
observations of C18O (J=2-1) toward L43, a protostellar object in transition
from Class I to II. The 225 GHz continuum emission shows a weak (~23.6 mJy),
compact (<1000 AU) component associated with the central protostar. Our
simulated observations show that it can be explained by dust thermal emission
arising from an envelope which has a hole or a constant intensity region within
a few hundred AU of the protostar. This suggests the disappearance or a lower
concentration distribution of the envelope on a small scale. The 12CO and 13CO
emission exhibit molecular outflows to the south and north. The C18O emission
shows two molecular blobs, which correspond to the reflection nebulosity seen
in near-infrared images, while there is no C18O emission associated with the
protostar. The near-infrared features are likely due to the scattering at the
positions of the blobs. The visible scattering features should result from the
optical thinness of the envelope material, which is consistent with the
less-concentrated distribution in the continuum emission. From single-dish
observations, we found that the mass of the envelope (~1.5 Msun) + protostar
(~0.5 Msun) is comparable with the virial mass of M_vir=1.0 Msun within 40
arcsec. This suggests that the envelope is likely gravitationally bound. We
suggest that the protostellar envelope of L43 has been disappearing by
consumption through accretion, at least in the close vicinity of the protostar.
