CHAPTER XXVIII 



PLANTS WITHOUT CHLOROPHYLL IN THEIR 

 RELATION TO MAN 



Problems : How molds and other fungi harm man. 

 What yeasts do for mankind. 



A study of bacteria with reference to the good and the harm they 

 do. 



Laboratory Suggestions 



Field work. Bracket fungi and chestnut blight. 

 Home experiment. Conditions favorable to the growth of mold. 

 Laboratory demonstration. Growth of mold, structure, drawing. 

 Home experiment or laboratory demonstration. Conditions unfavorable for 

 the growth of molds. 



Demonstration. Process of fermentation. 



Microscopic demonstration. Growing yeast cells. 



Home experiment. Conditions favorable for the growth of yeast. 



Demonstration. Tubercles containing nitrogen-fixing bacteria. 



Laboratory experiment. The value of preservatives. 



Saprophytic Fungi. — We have found that, on the whole, green 

 plants are useful to manldnd. But not all plants are green. We 

 have already seen the tremendous part that disease-producing 

 bacteria play in our lives ; and most of us are familiar with some 

 fungi, as the edible mushrooms and the so-called '' toadstools" 

 found in parks or lawns. These plants contain no chlorophyll. 

 They are as much dependent upon the green plants for food 

 as are animals. But the bacteria and the fungi require for the 

 most part dead organic matter for their food. This may be ob- 

 tained from decayed vegetable or animal material in soil, from 

 the bodies of dead plants and animals, or even from foods pre- 

 pared for man. Fungi which feed upon dead organic material 

 are known as sap'rophytes. Examples are the mushrooms, yeasts, 

 and molds. 



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