76 THE NATURE-STUDY REVIEW [i, 2, march, 1905 



just sufficient to pay for the tablets, printing, packing, and postage. The 

 author has no financial, only an educational, interest in the sale. This low 

 price is possible only because thousands of boxes are prepared at a time 

 by a manufacturing chemist. Large quantities have been purchased by 

 schools, and colleges find them most convenient for making the standard 

 Sachs' solution. Address Edward F. Bigelow, Stamford, Ct.— Managing 

 Editor.] 



A NATURE-STUDY LESSON WITH THE MOLDS 



BY PROFESSOR F. L. STEVENS, Ph.D. 

 North Carolina College of Agriculture and Mechanic Arts 



Molds of bread, cheese and fruits are only too common objects 

 in the household ; but little real knowledge prevails regarding their 

 nature, mode of origin or effects. This field of observation and 

 experimentation is so httle known that it is by most teachers either 

 never thought of at all or considered too difBcult to be of use to 

 the nature-study classes. Many simple and instructive experi- 

 ments, however, may be made in any school at no cost with these 

 simple plants, and much interest aroused and knowledge attained. 



Experiment i. To see whether any desired kind of mold can be 

 produced at will upon moist bread. 



Have one or two of the pupils place a slice of moist bread in a 

 glass fruit-can and heat it in a steamer just as you would in can- 

 ning fruit. Then seal it up while hot also just as you would in 

 canning fruit. Bring these cans to school. Also secure some 

 moldy cheese or bread. Suppose the cheese has on it a yellow 

 mold. Now the problem is to see if we can grow this yellow 

 mold in the bread. Heat the tip of a hat-pin in a match or lamp 

 flame, let it cool a second and dip it into the yellow mold. Now 

 draw this hat-pin across the bread in the jar. Then close the 

 can and watch it daily to see if the yellow mold comes in the 

 place you have planted it. Try this experiment with various 

 kinds of molds. 



Experiment 2. To see whether molds will develop if all in the 

 vessel are killed and all air excluded. 



Proceed as you did in Experiment i. Can the bread as you 

 would can fruit, and let it stay in the schoolroom for a few weeks 

 to see whether molds develop. Molds should not grow here 



