In the present investigation, the changes in motor cells of
Mimosa Pudica L. in the diurnal and nocturnal condition were studied from morphological and cytophysiological view-point. The results obtained are summarized below.
1) Tannin substances or tannin vacuoles in the plant tissue were fixed with Kaiser's solution, and a 0.5 per cent alcoholic solution of toluidin blue was discovered to be a specific agent for staining the tannin.
2) Kaiser's solution-toluidin blue method and Mallory's staining are found to tinge the motor tissue differently before and after the stimulus is received.
3) The motor tissue consists of three zones as follows:
P
1-zone: The most internal zone of the tissue. Cells of this have a large quantity of cytoplasm.
P
2-zone: Cells of this zone contain a small quantity of cytoplasm. Among the cells numerous intercellular spaces are seen.
P
3-zone: The concentric zone outside of P
1 and P
2 zones. This zone corresponds to the motor tissue in a strict meaning. The cell in this tissue has a thin cytoplasmic layer at its periphery.
4) Protoplasmic connections are observed in both P
2- and P
3-zones; these connections are frequently observed to traverse the central vacuoles after the stimulus is received.
5) Many air bubbles are found in the well developed intercellular spaces of P
2-zone. But after the movement they can scarcely be observed.
6) The attachment point of the pulvinus to the stem was cut with scissors, just after the movement when the under side of pulvinus had strongly contracted. From the cut end of the pulvinus a juice is secreted which includes tannin and potassium salt, certain nitrates and other chemical elements.
7) In the nocturnal condition, after the stimulus is received, dilute tannin substances and other crysalloids issue from the cell. These substances are fixed by Kaiser's solution in the intercellular spaces.
8) The discharge of above indicated substances is probably due to the fact that there is an increase of permeability of the cytoplasm in the nocturnal condition as well as in the diurnal.
9) Tannin substances infiltrate the cytoplasm after the stimulus is received in the diurnal condition. And in this condition the thin cytoplasm which is pressed closely to the cell wall is frequently observed.
10) In the diurnal condition the vascular bundle after receiving the stimulus is not stained by toluidin blue any more clearly than that of the anesthetized one.
11) In the nocturnal condition, the mixing of tannin and cytoplasm is observed in some parts of the motor tissue.
12) In the main pulvinus the quantity of tannin substances tend to decrease more in the nocturnal condition than in the diurnal.
13) These phenomena exhibit the different physiological conditions in the motor tissue depending upon whether it is day or night.
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