[en] The correlation between damage induced in somatic cells and that induced in germinal cells of the same genetic pool of individuals is important in establishing the possibility of extrapolation of this damage to the offspring. Drosophila melanogaster was used to compare cytologically the frequency of aberrations induced in the cells of somatic ganglia and in the spermatocytes I of males irradiated with 625 R X-rays. The spermatocytes were more sensitive than the gangliar cells to radiation: the aberrations induced in the spermatocytes I were three times more frequent than those induced in the ganglia. The distribution of the aberrations was, however, similar. The most important variable element lies in our observing no symmetrical exchanges in the spermatocytes. This result seems to us to be related to the fact that in the males of D. melanogaster there is no crossing-over