  We present the results of population syntheses for binary stars carried out
using the ``Scenario Machine'' code with the aim of analyzing events that may
result in long gamma-ray bursts. We show that the observed distribution of
morphological types of the host galaxies of long gamma-ray bursts can be
explained in a model in which long gamma-ray bursts result from the core
collapse of massive Wolf-Rayet stars in close binaries. The dependence of the
burst rate on galaxy type is associated with an increase in the rate of
stellar-wind mass-loss with increasing stellar metallicity. The separation of
binary components at the end of their evolution increases with the stellar-wind
rate, resulting in a reduction of the number of binaries that produce
gamma-bursts.
