On the basis of the parallel x-ray effects on different types of mutations (transgenation, translocations, inversion) one should search for a general mechanism that must exist in all these types of mutations. If one supposes for the origin of the mutations an attachment of chromosomes at the point of their accidental contact and then an irregular rupture at this point, it is possible to conceive of a general scheme for transgenations, trans-locations, duplications, deficiencies and also inversions, as is shown in the figures.