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dioular stick, no use being made of the leaves, but if the footstalk 

 of a leaf be rubbed witli a thin twig a few times on any side, it will 

 in the course of a few hours bend on that side, the petioles will 

 curl round, and by the hook so made the young leaves are enabled 

 to catch twigs they come in contact with. In the case of Solanum 

 jasminioides, which is a leaf climber, it was noticed that when a 

 petiole clasped a support, it increased in thickness in three or four 

 daj's, and after a time became rigid ; and on comparing a thin trans- 

 verse slice of the petiole, with one from the older leaves beneath, 

 which had not clasped anything, its diameter was found to be doubled 

 and its structure greatly changed. In tlic petiole in its ordinary 

 state is a semilunar band of cellular tissue slightly diffei'ent from 

 the cortical layer, and including three groups of vascular bundles ; 

 on the other hand in the section of the petiole which had clasped 

 a stick, the two upper ridges had .become less prominent, and the 

 gi'oups of woody vessels increased in diameter, whilst the semilunar 

 band had been converted into hard woody tissue with lines radiating 

 from the centre. 



It is presumed that plants become climbers to reach the light, 

 and to expose a large surface of leaves to its action and to fresh 

 air. This is etfected by many, with wonderfully little expenditure 

 of organized matter, their tendrils possessing the power of move- 

 ment on contact with a stick hold-fast or they can lengthen so as to 

 sweep a wide circle. "We see then how high in the scale of 

 organization a plant may rise, when we look at one of the tendril 

 bearers. It gets ready for action almost as a polype puts out its 

 tentacles to seize its prey. If a tendril be displaced, it is acted 

 upon by the force of gravity, and rights itself. It bends towards 

 the light or away from it, as 7nay be most advantageous. When the 

 tendril strikes some object it curls round aud tightly grasps it, and 

 in the course of a few hours it contracts its spire, dragging np the 

 growing plant after it. By growth the tissues become wonderfully 

 strong and durable. 



Stems, petioles, flower peduncles, and tendrils, spontaneously 

 revolve, the motion being contingent on the youth and vigorous 

 health of the plant. 



The term nyctitropic, or night turning, may be applied to 

 both leaves and flowers when their movements are modified by 

 alternations of day and night. The petals of flowers when they 

 go to sleep, move either upwai'ds or downwards as may be seen 

 respectively in the daisy, and pyrethrum, or field chrysanthemum. 

 The leaves not only do the same, but in the case of some compound 

 ones, move forwards towards the apex, or backwards towards the 

 base, from the movement of the pluvini, or joints, which become 

 more turgescent on the opposite sides. Many plants grow in such 



