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The morphological types of galaxies in nine clusters in the redshift range0.1<z<0.25 are derived from very good seeing images taken at the NOT and the LaSilla Danish telescopes. With the purpose of investigating the evolution of thefraction of different morphological types with redshift, we compare our resultswith the morphological content of nine distant clusters studied by the MORPHSgroup, five clusters observed with HST-WFPC2 at redshift z = 0.2-0.3, andDressler's (1980) large sample of nearby clusters. After having checked thereliability of our morphological classification both in an absolute sense andrelative to the MORPHS scheme, we analyze the relative occurrence ofelliptical, S0 and spiral galaxies as a function of the cluster properties andredshift. We find a large intrinsic scatter in the S0/E ratio, mostly relatedto the cluster morphology. In particular, in our cluster sample, clusters witha high concentration of ellipticals display a low S0/E ratio and, vice-versa,low concentration clusters have a high S0/E. At the same time, the trend of themorphological fractions and ratios with redshift clearly points to amorphological evolution: as the redshift decreases, the S0 population tends togrow at the expense of the spiral population, whereas the frequency of Esremains almost constant. We also analyze the morphology-density (MD) relationin our clusters and find that -similarly to higher redshift clusters- a good MDrelation exists in the high-concentration clusters, while it is absent in theless concentrated clusters. Finally, the comparison of the MD relation in ourclusters with that of the D97 sample suggests that the transformation ofspirals into S0 galaxies becomes more efficient with decreasing local density.Comment: 24 pages including 11 figures and 4 tables, accepted for publication  in Ap

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