Abstract
The mitotic frequency in dormant cotyledonary buds of light-grown sunflower (Helianlhus annUU8 L.) plants is low. It may be sharply reduced, either by floating detached budR on a mineral solution for 6-24 hI', or by darkening plants for 3 days. This lowered mitotic frequency can be increased by the supply of sucrose alone, either to detached buds via the flotation medium, or to attached buds via the hypocotyl.