. Practical text-book of plant physiology. Plant physiology. RATE OF TRANSMISSION OF IMPULSES IJ of the petiole with the main stem. The angles should be meas- ured exactly with a protractor. The influence of the stimulus may be conducted up or down the stem to other leaves in which it will be transmitted from the bases toward the apices, causing the movement of the petiole first and of the leaflets last. The demonstration of reac- tion to shock may also be made with Biophytum sensiti- vum. In this plant the leaves are simply pinnate. A stimu- A ( lus applied to the terminal pair of leaflets is
. Practical text-book of plant physiology. Plant physiology. RATE OF TRANSMISSION OF IMPULSES IJ of the petiole with the main stem. The angles should be meas- ured exactly with a protractor. The influence of the stimulus may be conducted up or down the stem to other leaves in which it will be transmitted from the bases toward the apices, causing the movement of the petiole first and of the leaflets last. The demonstration of reac- tion to shock may also be made with Biophytum sensiti- vum. In this plant the leaves are simply pinnate. A stimu- A ( lus applied to the terminal pair of leaflets is transmitted the length of the rachis only, and does not pass into the other Fig. 3. Biophytum sensitivum. A, leaves attached to the crown, A> A> leaflets after mechanicai stimulation. ordinarily, although Haber- landt1 demonstrated transmission through stems and flower stalks. A notable feature of the reaction in this plant is the fact, that in response to a single stimulation the leaflets close toward each other in pairs through a small arc, and then after a short interval make a second movement in the same direction. 19. Rate of Transmission of Impulses or Stimulus-effects. With watch in hand snip the terminal pair of pinnules of a normal leaf of Mimosa by means of a pair of scissors or forceps, and note the number of seconds elapsing before each pair of pin- nules closes together as the impulse traverses the midrib, and be- fore the whole leaf falls down by the action of the main pulvinus at its base. Next note the time elapsing before the impulse reaches the leaves above and below the one originally stimulated. Measure the distance from the point at which the stimulus was applied to every point of action and estimate the rate of trans- mission in the different organs. If the stimulus applied does not 1 Ueber die Reizbewegungen und die Fortpflanzung bie Biophytum. Ann. Jard. Bot. d. Buitenzorg. Second Supplement, p. 33. 1898. See also MacDougaL Transmission of impulse
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