Abstract:The secretory cavity in fruits of Evodia rutaecarpa (Juss.) Benth. developed schizogenously through a separation of the walls of the central initial cells. Electron micrographs revealed that in the early stages of cavity development there was an apparent increase in the number and volume of the plastids in which esmiophilic droplets and tubular dements were observed. This suggested that the essential oils might be synthesized in the plastids.. The essential oils were then transport ed through the plastid membrane to the surrounding endoplasmic reticulum or into the vacuoles, becoming vesicles approaching the plasmalemma, and finally releasing their contents into the oil chamber by plasmalemma invaginations.