  In this paper, we study Ruelle's probability cascades in the framework of
time-inhomogeneous fragmentation processes. We describe Ruelle's cascades
mechanism exhibiting a family of measures $(\nu_t,t\in [0,1[)$ that
characterizes its infinitesimal evolution. To this end, we will first extend
the time-homogeneous fragmentation theory to the inhomogeneous case. In the
last section, we will study the behavior for small and large times of Ruelle's
fragmentation process.
