  We discuss the evaluation of Luria-Delbrueck fluctuation experiments under
Bellman-Harris models of cell proliferation. It is shown that under certain
very natural assumptions concerning the life-time distributions and the
offspring distributions of mutant and non-mutant bacteria, the suitably normed
and centered number of mutants contained in a large culture of bacteria
converges to a stable random variable with index 1. The result obtains under
the assumption that the mutation under consideration is neutral in the sense
that on average, mutant cells produce the same number of offspring as
non-mutant cells.
