  The Hawking radiation emits all species of particles, but the
Bekenstein-Hawking entropy is independent of the number of the species of
particles. This is the so-called species problem --- a puzzling problem for a
long time. In this paper, we suggest a solution to this problem. A result of
the scheme is that the black hole atmosphere has a mass equaling 3/8 mass of a
classical Schwarzschild black hole, which agrees with 't Hooft's brick wall
model.
