FLOWERING PLANTS 131 



desired by man, sometimes to the detriment of the seeds them- 

 selves. The lessons .may include the structure of some of the 

 following kinds of fruits. Let each pupil have at least one speci- 

 men of the fruit studied. Have Ijim cut into it and examine 

 carefully all its parts and just how they are arranged in reference 

 to each other. 



The peach, plum, cherry, apricot and raspberry. (These are 

 called by the botanists drupes). 



Gooseberry, orange, grape. (These are known as berries). 



The apple-like fruits. 



The melons, cucumber and squash. 



The tomato. 



The fig, the pod fruits, the winged fruits (maple), the straw- 

 berry. Any kind which any pupil may find, either wild or culti- 

 vated, should receive attention. 



Ripening of Fruits. 



In some of the upper grades the question of what takes place 

 in a ripening fruit may well be investigated. It has just been 

 seen how the leaves in the presence of sunlight make starch out 

 of carbonic acid and water. Further it was shown that starch in 

 the leaves is changed to sugar or into some other soluable substance, 

 and may then be distributed to different parts of the plant and 

 changed to starch again. 



The fruits serve to illustrate some of these changes. A few 

 simple experiments can be performed which will make clearer 

 these facts. A good test for the presence of starch is needed. A 

 solution of iodine is used for a test for starch. A solution of iodine 

 gives starch a blue color and thus proves its presence even where 

 mixed with other substances. A solution of iodine is made by 

 dissolving a few crystals of iodine in a solution of iodide of potas- 

 sium. 



To show how the iodine acts on starch, a drop may be placed 



