90 AGRICULTURE ON THE PACIFIC SLOPE 



very high or very low temperature may ruin certain 

 crops. 



Does light help or hinder growth? Place two lots of 

 seeds (or two potatoes) in different pots. Place one in 

 strong light. Keep the other covered with a box. 

 Keep the warmth and moisture as nearly as possible the 

 same for both. Which lot grows faster (see figures 66 

 and 67) ? 



How food is stored up in the plant. All plants which 

 live over winter store up food for future growth. Some 

 store it in their roots (sugar beet, turnip, sweet potato), 

 some in the part of the stem which is underground 

 (potato), or in leaves underground (onions and other 

 bulbs). Some store it above ground in leaves or stems. 

 Here it is not so safe from animals and must often 

 be protected by sharp spines, teeth, or a disagreeable 

 taste. You may see this well illustrated in the cactus. 



Trees store up a great deal of food in their trunks in 

 winter. The wood and bark is sometimes ground up 

 and mixed with flour in times of famine. The sugar of 

 the sugar maple is such stored food. 



Test the wood of oak, willow, hazel, or lilac for starch 

 during the winter. Some trees (birch) store their food 

 as fat. Test also various roots for food (see page 83). 



