I2O 



Lessons in Nature Study. 



What will happen if I lay this half apple away for a 

 while ? Yes, the cut side turns brown. Why ? " Because 

 the air is beginning to rot it." Will apples rot if no air can 

 reach them ? " No." When sealed up in cans, they will 

 keep a long time from spoiling. 



Now we will put the apple in this glass bottle and crush 

 it with this stick. Charlie may crush it to pulp. We will 

 place it here on the window-sill until to-morrow. 



FIG. 33*. 



II. FERMENTATION. 



Children,. come up close and see what has happened to 

 the apples we crushed and put in this bottle. " It has 

 turned brown." " It is rotting." " It smells sour." " There 

 are bubbles on it." " There are bubbles all through it." 



Are these air-bubbles ? " No, it smells very sour." " It 

 smells like cider." 



What is the apple-pulp doing? "It is rotting." "It is 

 working." 



