Some attempts were made on the petiole of
Mimosa pudiea to examine the microscopical structure of the epidermal system and the parenchyma of the cortex.
1) On the upper and on the side surface of the petiole, many stomatal apparatus, some glandular hairs and pointed hairs are distributed.
2) The stoma is composed of two small guard cells and the latter are again surrounded by large subsidiary cells. And just under or adjacent to the stoma, several small special cells are observed.
3) The sub-stomatal air chamber of the stomata opens the large intercellular space of the dorsal part of the cortex. This space is the schizogenous intercellular space.
4) The large spaces of the petiole open into the intercellular spaces of the primary pulvinus, but do not open into the intercellular space of the pinna-rachis.
5) In these spaces, the parenchymatous cells are arranged in longitudinal rows. These cells have chloroplasts, starch grains and small tannin vacuoles. From each tannin vacuole one or two threadlike vacuoles protrude into the large central vacuole.
6) The small tannin vacuole and the threadlike vacuole were the same characteristics. Both take chrome salts, and are stained with neutral red, chrysoidin and other basic dyes indicating that the threadlike vacuoles are mere modifications of ordinary tannin vacuoles. The threads shrink by the action of caffeine solution.
7) The threadlike vacuole of one cell has a connection with that of the neighbouring cell. These connections do not occur lengthwise, but between the cells side by side.
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