Abstract: Light microscopical observation of thin sections revealed that the initials of secretory cavities in Poncirus trifoliata (L.) Raf. originated from parenchyma cells below the epidermis in early stages of development. The cavity lumen appeared in the center of the initials and gradually enlarged during subsequent development. Concurrently the ceils surrounding the central space differentiated into secretory cells and sheath cells. The developed cavities of fruit ,stem and leaf consisted of 2–5 layers of sheath cells and 2–3 layers of secretory cells surrounding a spherical space. The secretory cells lining the space were observed to remain intact throughout the plantt s life. On the basis of comparative studies with the aid of different kinds of fixatives, embedding media and sectionings,it was suggested that the ,manner of formation of the lacunao of secretory cavities in fruit peels of P. trifoliata, Citrus reticulata and C. sinensis were different. However,as seen in thin sections the secretory cavities of all the 3 species developed schizogenously. Our result with reference to views of other authers concluded the existance of a common schizogenous cavity formation in Rutaceae.

Key words: Poncirus trifoliats, Secretory cavity