226 NATURE STUDY AND AGRICULTURE 



point of a pin on the moldy orange, now insert it about one 

 third its length in the good orange and leave it there. 

 Watch developments. What is the first indication that 

 mold is growing on the inside ? The orange will become 

 soft around the pin. How long before the mold spores 

 begin to show on the outside ? In order to show that this is 

 not due to the puncture of the pin, sterilize a pin by putting 

 it in hot water and place it in the opposite side of the 

 orange. Do this when you set in the first pin. Tie a 

 label to each pin so that you will know which had the mold 

 spore on it. You will get quicker results by setting the 

 orange in a jar and covering the jar. Try planting the 

 spores of a rotten apple in a sound one. Rub some of the 

 spores on the unbroken skin of the apple or orange. Do 

 the spores grow? 



Where did the mold come from on the first piece of 

 bread? The spores must have been on it when it was 

 moistened and put under the tumbler. They must have 

 been in the air. Why does stale bread mold more quickly 

 than fresh? Why does canned fruit mold? Can mold 

 spores be killed? 



Pour boiling water over a small piece of stale bread and 

 turn over it a tumbler in which you have just dashed boiling 

 water. At the side of this place a piece of the same kind 

 of bread that is soaked in cold water and has a cold tumbler 

 turned over it. Watch for developments. Why do you 

 pour boiling water in fruit jars before canning the fruit? 

 Why should lids of the jars be sterilized in the same way? 



Soak a piece of fresh bread in a half glass of water in 

 which you have placed a few drops of formalin. Plant 

 spores on this as you did on the other piece of bread. Do 



