Rhodamine-labelled phalloidin stains components in the chromosomal spindle fibres of crane-fly spermatocytes and Haemanthus endosperm cells. In crane-fly spermatocytes and Haemanthus endosperm, all metaphase and anaphase chromosomal spindle fibres were stained with rhodamine-labelled phalloidin. In crane-fly spermatocytes, each kinetochore was stained with rhodamine-labelled phalloidin at diakinesis of prophase and after colcemid caused metaphase spindles to depolymerize. Since phalloidin stains actin filaments, the distributions of rhodamine-labelled phalloidin-stained material in crane-fly spermatocytes and Haemanthus endosperm suggest that actin filaments might interact with microtubules to produce forces that move chromosomes during cell division, either directly or via an intermediate motor molecule.