MOVEMENT IN PLANTS. 



a number of soaked seeds (e.g. Sunflower) between the 

 cloth and the surface of the pot. Hang the pot up 

 horizontally by means of two loops of string, in such a 

 way that the zone of seeds is horizontal. After a few 

 days note that the roots grow down and follow the curved 

 surface of the pot, instead of leaving it in order to grow 

 vertically downwards. If the porous pot is suspended in a 

 vessel containing some water, however, the roots grow 

 vertically downwards, instead of following the curved 

 surface of the pot. 



(d) In the middle of a box of not too wet soil place a 

 flower-pot, first plugging the hole in the bottom by a cork. 

 Put some soaked seeds in the soil around the pot, but do 

 not water the soil ; pour water into the pot, however, and 

 fill it up daily as the water evaporates. After a few days 

 remove a seedling carefully, and note that its root has 

 curved towards the pot of water. 



V. EXPERIMENTS WITH TWINING STEMS. 



314. Material for Study. Many experiments on 

 twining can be made with the Scarlet Runner, but other 

 twiners should also be used, e.g. Hop, Convolvulus ; potted 

 plants are required for most of the experiments. 



Sow Runner seeds in pots of garden soil ; as the seed- 

 lings grow up, leave only the strongest one in each pot. 

 Note that the first few internodes of the stem grow erect 

 and firm, but the later ones begin to bend so that the tip 

 of the shoot nods to one side and becomes horizontal or 

 even directed a little downwards. Get ready several vigor- 

 ously growing plants. 



315. Revolving Movement of Stem Tip. Take a 

 plant in which the upper part of the shoot hangs over for 

 a few inches. Tie the lower part of the stem to a stick 

 placed in the soil, set the pot on a sheet of paper and 

 record the position of the tip of the shoot. 



This may be done in several ways : (1) by drawing lines 

 on the paper radiating from the centre of the pot, so as to 



