+--------------------------------------------------------------------+ |Description of | Action. | Effect observed. | | tissue. | | | +---------------+------------------------+---------------------------+ |I Tissue |Stimulus causes increase|Expansion or enhanced rate | | sub-tonic. | of internal energy. | of growth, _e.g._, | | | | _Pileus_ of _Coprinus_ | | | | drooping in darkness, | | | | made re-turgid by light. | | | | Renewed growth of dark | | | | rigored plant exposed to | | | | light. | |II Normally |A 1. Moderate light, |1. Curvature towards light,| | excitable | causing excitatory | _e.g._, flower bud of | | organ under| contraction of proximal| _Crinum_. | | unilateral | and positive expansion | | | light. | of distal. | | | A. Organ |A 2. Strong light. |2. Neutralisations, _e.g._,| | radial. | Excitatory effect | seedling of _Setaria_. | | | transmitted to distal, | | | | neutralising first. | | | |A 3. Intense and |3. Reversed or negative | | | long-continued light. | response, _e.g._, seedling| | | Fatigue of proximal and| of _Zea Mays_. | | | excitatory contraction | | | | of distal. | | | B. Dorsi- |B 1. Excitatory |1. Positive response, | | ventral | contraction of proximal| _e.g._, upward folding of | | organ. | predominant, owing | leaflets in so-called | | | either to greater | "diurnal sleep" of | | | excitability of | _Erythrina indica_ and | | | proximal or feeble | _Clitoria ternatea_. | | | transverse conductivity| | | | of tissue. | | | |B 2. Transmission of |2. Negative response, | | | excitation through | _e.g._, downward folding | | | highly conducting | of leaflets in so-called | | | tissue to more | "diurnal sleep" of | | | excitable lower or | _Biophytum_ and | | | distal. Greater | _Averrhoa_. | | | contraction of distal. | |