The association of microtubules with mitotic holokinetic chromosomes of Tetranychus urticae Koch was investigated in serial ultrathin sections. Reconstructions from 14 series showed that 60–100 microtubules were associated with the entire poleward surfaces of the chromosomes. In the telophase of early developmental stages the chromosomes were decondenseed into separate micronuclei, containing at least one nucleolus. From these morphologic data, the fate of induced chromosome fragments, described in earlier papers, is surmised to depend on events in interphase as well as in mitosis.