6^6 THE POPULAR SCIENCE MONTHLY. 



These various contrivances have been studied by more than one 

 German naturalist, as well as by my father,, in whose book on the 

 " Habits of Climbing Plants " very full details upon this subject will 

 be found. 



Climbing plants are, first of all, divided roughly into those which 

 twine and those which do not twine ; twiners are represented by the 

 hop and the honeysuckle, and all those plants which climb up a stick 

 by winding spirally round it. Those which are not twiners that is, 

 which do not wind spirally round a stick are such as support them- 

 selves by seizing hold of any neighboring object with various kinds of 

 grasping organs ; these may be simple hooks, or adhering roots, or 

 they may be elaborate and sensitive tendrils, which seize hold of a 

 stick with a rapidity more like the action of an animal than of a plant. 

 We shall come back to this second class of climbing plants, and shall 

 then consider their various kinds of seizing organs. I merely wish 

 now to insist on the importance of distinguishing between these two 

 methods of climbing, in one of which the plant ascends a support by 

 traveling spirally round it; in the other, fixes on to the support by 

 seizing it at one place, and continuing to seize it higher and higher up 

 as its stem increases in length. 



I have heard the curator of a foreign botanic garden bitterly com- 

 plain of his gardeners that they never could learn the difference be- 

 tween these two classes of climbing plants, and that they would only 

 give a few bare sticks to some tendril-bearing plant, expecting it to 

 twine up them like a hop, while the plant really wanted a twiggy 

 branch, up which it might creep, seizing a twig with each of its deli- 

 cate tendrils, as it climbed higher and higher. These two kinds of 

 climbers twiners and non-twiners may be seen growing up their 

 appropriate supports in any kitchen-garden where the scarlet-runners 

 twine spirally up tall sticks, while the peas clamber up the bushy 

 branches stuck in rows in the ground. 



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 anything remarkable 

 about our hop ; it has sent out a straggling 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. Supposing that we have noticed the shoot, when it began 

 to bend over, pointed toward the window say a north window and 

 that, when 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 discovered the curious fact that the hop-plant has a certain power 



