100 AGRICULTURE FOR BEGINNERS 



EXERCISE 



Why do things mold more readily in damp places? Do you now 

 understand why fruit is heated before it is canned? Try to grow 

 several kinds of mold. Do you know many edible fungi ? 



Transfer disease from a rotten apple to a healthy one and note the 

 rapidity of decay. How many really healthy leaves can you find on a 

 strawberry plant ? Do you find any spots with reddish borders and 

 white centers ? Do you know that this is a serious disease of the 

 strawberry? What damage does fruit mold do to peaches, plums, 

 or strawberries ? 



Write to your Experiment Station for Bulletins on plant diseases 

 and methods for making and using the Bordeaux Mixture. 



SECTION XXVI YEAST AND BACTERIA 



Can you imagine a plant so small that it would take one 

 hundred plants lying side by side to equal the thickness 

 of a sheet of writing paper ? There are plants that are 

 so small. Moreover, these same plants are of very great 

 importance to man in two ways. Some of them do him 

 great injury, while others aid him very much. 



You will recognize their importance when I tell you that 

 certain of them in their habits of life cause great change 

 in the substances that they live in. For example, when 

 living in a sugary substance, they change the sugar into 

 a gas and an alcohol. Do you remember the bright bub- 

 bles of gas you have seen rising in sweet cider or in wine 

 as it soured ? These bubbles are caused by one of these 

 small plants, the yeast plant. As the yeast plant grows 

 in the sweet fruit juice, alcohol is made and a gas is given 

 off at the same time, and this gas makes the bubbles. 



