How a Tree Lives 75 



is pure while that coming from your lungs is charged with carbonic 

 acid gas. 



3. (Demonstration.) Some cotton wool is soaked with methy- 

 lated spirit and placed on a small saucer floating on coloured water. 

 The wadding is set alight and is quickly covered with a glass jar. 

 Notice what happens as the wadding burns. The air that is left in 

 the glass jar is shaken up with a little clear lime water. What 

 happens to the lime water ? Write an account of the experiment in 

 your own words and explain what you learn from it, giving diagrams. 



4. You are given leaves, parts of which have been kept from the 

 light for 24 hours by coverings of tinfoil. Boil them in water, but 

 only for one minute, this kills them; then place them in alcohol 

 to get rid of the green colour. Now if you put them into iodine you 

 will find that those parts of the leaves which were exposed to the 

 light turn dark blue, showing the presence of starch. Put your 

 stained leaves into clear water and leave them for inspection. (This 

 experiment with leaves partly covered with tinfoil should be repeated 

 in the summer when the sunlight is brighter and summer leaves, e.g. 

 clover or nasturtium, can be obtained.) 



HOME WORK. 



Write a short essay, not more than three pages, on " How Plants 

 feed and breathe." 



CHAPTER IX 



THE ROOT 



Season. Third week in February. 

 Materials required for each pupil. 



A mustard seedling seven days old. (The seedlings 

 can be grown in moist air by fitting a piece of moist 

 blotting paper inside a tumbler, and pushing the seeds 



