12 NATURAL HISTORY READER. 



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garden, where the scarlet-runners twine spirally up tall 

 sticks, while the peas clamber up the bushy branches stuck 

 in rows in the ground. 



3. A hop-plant will supply a good example of the mode 

 of growth of true twining plants. Let us imagine that we 

 have a young hop-plant growing in a pot ; we will suppose 

 that it has no stick to twine up, and that its pot stands in 

 some open place where there are no other plants to interfere 

 with it. A long, thin shoot will grow out, and, not being- 

 strong enough to support itself in the upright position, will 

 bend over to one side. So far we have not discovered any- 

 thing remarkable about our hop ; it has sent out a strag- 

 gling shoot, which has behaved as might be expected, by 

 falling over to one side. But now, if we watch the hop- 

 plant closely, a very remarkable thing will be seen to take 

 place. 



4. Supposing that we have noticed the shoot, when it 

 began to bend over, pointed toward the window — say a 

 north window — and that, wdien we next look at it after 

 some hours, it points into the room, that is to say, south, 

 and again north after another interval, we shall have dis- 

 covered the curious fact that the hop-plant has a certain 

 power of movement by which its shoot may sometimes 

 point in one direction, sometimes in another. But this is 

 only half the phenomenon, and, if we examine closely, we 

 shall find that the movement is constant and regular, the 

 stem first pointing north, then east, then south, then west, 

 in regular succession, so that its tip is constantly traveling 

 round and round like the hand of a watch, making on an 

 average, in warm August weather, one revolution in two 

 hours. Here, then, is a most curious power possessed by 

 the shoots of twining plants, which is worth inquiring fur- 

 ther into, both as regards the way in which the movement 

 is produced, and as to how it can be of any service to the 

 plant. 



