58 Plants and their Ways in Sorith Africa 



Soak strips of paper in cobalt chloride. Dry thoroughly, 

 and notice how they change from red to blue as they dry. 

 Dry the inside of the jar containing the plant. After remaining 

 in the bell-jar for awhile the paper changes back to red. This 

 also shows that vapour is passing from the leaves. 



This pretty experiment should not be omitted. Cobalt chloride may 

 be obtained from the chemist. Sixpennyworth will prepare sufficient 

 paper to last some time. It will keep, and the same piece may be used 

 repeatedly. 



Place under the bell-jar fruits of Erodium or Pelargonium 

 and watch them uncoil; remove, dry in the sun, and repeat 

 the experiment. 



Place a leafy shoot in a glass U-tube (a straight piece of 

 glass may be heated and bent the required shape.) Connect 

 the shoot to the tube with rubber tubing so that no air can 

 enter. The tube should be filled from the other end with 

 water. When the water has been nearly drawn out of one arm, 

 pour in mercury. The mercury, which is very heavy, will be 

 raised higher in the arm of the tube containing the plant than 

 in the other, so the leaves can do some heavy lifting. 



Does water pass from leaves in any form but 

 vapour ? If so, it must be in drops. Place a pot of germi- 

 nating Indian corn or oats under a bell-jar overnight. The 

 next morning notice the tip of each blade where there are 

 small holes through which water can pass in drops. 



In early morning a field of young corn is very beautiful 

 when — 



" in each pettiest personal sphere of dew 

 The summ'ed morn shines complete as in the blue 

 Big dewdrop of all heaven," 



They are not dewdrops, for they are there when no dew is 

 formed on other plants. Other plants show the same nicely. 

 See the drops on TropcBolewn (Nasturtium) plants where 

 openings on the leaves are placed at the end of each strong 

 vein. 



Does vapour pass off in equal amount from both 

 leaf surfaces P Place an apricot leaf between two sheets of 



