448 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



the terminal part of a tendril, it will almost immediately show signs of 

 curvature, and will be fully curved in a couple of minutes. A perfectly 

 smooth body, such as a dust-free, gelatine-coated rod, will not produce 

 curvature. These tendril-bearing plants may be looked upon as among 

 the highest in the scale of plant organisation. A plant of this kind first 

 places its tendrils ready for action, just as a polypus places its tentacles. 

 During several days the tendril searches for something to cling to, revolv- 

 ing the while with a steady motion. On striking a suitable object, it 

 quickly turns round and firmly grasps it. In two or three hours the 

 tendril contracts into a spring and drags up the stem. Movement on the 

 part of this particular tendril now ceases, it having completed its work in 

 an admirable manner. 



The effect of light on plants is a striking example of their conscious- 

 ness, and is in many ways similar to its effect upon animals. The 

 bending of plants- towards light is well known, but it has been proved that 

 there is no close parallelism between the amount of light which acts on 

 a plant and its degree of curvature. One's own personal experience shows 

 us that the retina, after being exposed to a strong light, feels the effect for 

 some time ; and, in some experiments carried out by Darwin, a plant 

 continued to bend for half an hour towards the side which had been 

 illuminated. Some plants which had been kept in the daylight during the 

 previous day and morning did not move towards an obscure lateral light, 

 as did others which had been kept in complete darkness, thus showing an 

 analogy with the fact that the retina cannot perceive a dim light after 

 having been exposed to a bright one. 



One striking element in plant consciousness is the localisation of 

 sensitiveness, and the power of transmitting an influence from the excited 

 part to another, which consequently moves. In the case of the Drosera, 

 when the tip of a gland is irritated, the basal and not the upper part of 

 the tentacle bends. The sensitive filament of DioncBa also transmits the 

 stimulus without itself bending. 



The power of movement for a specific purpose — movement, too, which 

 is unaffected, and cannot be caused, by outside stimulus — is strikingly 

 seen in the many examples among plants of conscious sexual intercourse. 



This was observed as long ago as the time of Erasmus Darwin, who 

 wrote a poem called " The Love of Plants." 



The vegetable passion of love is seen in the flower of the Pamassia 

 (Grass of Parnassus), in which the males alternately approach and recede 

 from the females. In the Nigella, or Love-in-the-Mist, the female flowers 

 grow on longer stalks than the males, and, to use Darwin's words, "in 

 which the tall females bend down to their dwarf husbands." 



The Gloriosa superba, or Creeping Lily, a South African plant, is 

 another well-marked illustration of this power of conscious movement. In 

 this plant, first one set of three stamens come to maturity, and then three 

 others, of which Darwin in the above poem wrote : 



Proud Gloriosa led three chosen swains, 

 The blushing captives of her virgin chains, 

 When Time's rude hand a bark of wrinkles spread 

 Round her weak limbs, and silvered o'er her head ; 

 Three other youths her riper years engage, 

 The flatter'd victims of her wily age. 



