132 MANUAI, OF NATURE STUDY. 



11. Study measurements of leaves, tendrils, etc. 

 Have a sensitive plant. Mimosa pudtca, if possible, 

 brought in tlie school-room, and let tbe children 

 touch the leaflets and observe them to immediately- 

 close together, and after a time regain their original 

 position. Why does the plant behave in that way? 

 This explanation of leaf movement, either from 

 touch or influence of light or darkness, rain or sun- 

 shine, is too difficult for a work of this kind. For 

 full explanation of plant movement, the teacher is 

 referred to pages 532-539, vol. I, of Kemer and 

 Oliver's Natural History of Plants; also vol. II, 

 Goodale's Physiological Botany, pages 397-424. 

 See another chapter of this book for sleep move- 

 ment of plants. Darwin says that all growing parts 

 of a plant are in constant movement around one 

 common center from right to left, or the opposite 

 direction, from left to right. The tendril and 

 twiner are only exaggerations of this common 

 movement. Encourage the children to observe 

 direction of grape tendril, pea climber, bean, wista- 

 ria, hop vine, morning glory or any other vine in 

 the vicinity, and report. 



Can a plant bore its roots into the ground any 

 easier by this worming process than by straight 

 pushing? Try to push a tender sprout or tender 

 twig straight into the ground. Now try to work it 

 back and forth. Which is the most successful way? 



