TO LEARN ABOUT SOME DESTRUCTIVE FUNGI 193 



They may get into canned substances put up in sugar and cause 

 them to " work," giving them a peculiar flavor. But they can be 

 easily killed by heating to the temperature of boiling. On the other 

 hand, yeast gives us leavened bread. 



Many interesting experiments with yeast may be tried as home 

 projects. For excellent suggestions, see Conn's Bacteria, Yeasts, 

 and Molds in the Home, pp. 274-278. 



Practical Exercise 4. How may yeasts be useful to man ? Where are yeasts 

 found? Give proofs. What products are formed when bread rises? What 

 becomes of these products? It is said that yeast plants are at once the 

 friends of man and yet make him their slave. Explain what this means. 



Self-Testing Exercise 



Yeasts cause (1) by changing (2) into (3) 



(4) and (5) . An enzyme called (6) causes 



fermentation (7) also cause bread to rise, because of the 



bubbles of (8) (9) formed during their (10) 



growth when the (11) is put in a (12) place. 



PROBLEM V. TO LEARN ABOUT SOME DESTRUCTIVE FUNGI 



Most of us are familiar with some fungi, as the edible mushrooms 

 and the so-called " toadstools " found in parks or lawns. We 



L. W. Brownell 

 These poisonous toadstools (amanita muscaria) are found during the summer and early 

 autumn along roadsides near trees, in groves, and in woods. 



