MOVEMENTS OF PLANTS 37 



But I am not going to deal with microscopic 

 matters, but rather with things on a bigger 

 scale which can be seen with the naked eye. I 

 will begin by trying to show that very obvious 

 movements are to be seen in every kitchen garden, 

 or in every garret window, where a scarlet runner is 

 grown for its red flowers' sake. 



In a scarlet runner the shoot is not completely 

 vertical, but bends over to one side. To record the 

 movements of the plant a series of photographs may 

 be taken vertically from above the plant, so that 

 the end of the shoot shows like the hand of a watch 

 against a sort of clock-face on which the points of 

 the compass are marked. Such photographs show 

 how the shoot swings round in its instinctive search 

 for another stick to climb. 



This well-known movement is performed by a 

 co-ordinated series of curvatures, the exact nature of 

 which need not trouble us now. Let us rather 

 consider the less obvious power of co-ordination 

 which enables a plant to grow upwards in a straight 

 line. Think of a forest of pine trees, hundreds of 

 thousands of them, all growing vertically up 

 towards the sky. Here is a clear case of movement, 

 for the leading shoots were once but a few inches 

 from the ground, and now they are crawling along 

 vertical lines 100 feet up in the air. It may be 

 said that this is mere increase in size, not movement 

 in the ordinary sense. But it may be made plain 

 that the trees could not grow in this way had they 

 not a power of curvature, to which the term 

 movement cannot be refused. 



As it is not easy to experiment on pine trees 



