Light propagation is a stone in the construction of A. Einstein SR theory and the comment he made in 1921 is still relevant. The existence of or non existence of a medium for the light propagation has not yet been given a clear answer. It is admited nowadays that light propagates in vaccum", without knowing its nature. Even if we call "vaccum" the medium for the propagation of light, to not say "ether", it is still a mystery how this medium behaves inside transparent matter in motion relative to space. The negation of the term "ether" comes from debates about experiments made in 19th century when stellar aberration was discovered and which gave rise to the Augustin Fresnel proposition of the "entrainment of ether by matter". Hyppolite Fizeau validated this concept with an experiment in which light is propagating through moving water and which was confirmed by Michelson, a few years later, in water and air. To have a clearer idea of the cohabitation of the two entities, matter and ether, Michelson initiated the issue of the behaviour of light in moving matter through ether ("ether wind") which was not treated by Fizeau experiment. The Michelson and Morley experiment was devoted to demonstrate the effect of the earth's motion through space on light propagation. The results obtained are still in controversial. In this paper we shows that the results obtained by Michelson, which were not null, can be explained by a new model of light propagation in transparent matter in motion through space.