EXERCISE 66 



A STUDY OF FUNGI 



Statement. Fungi are found on both living and decaying organic matter, and are present in abun- 

 dance practically wherever there is dead organic matter. Many fungi attack plants and break down the 



living tissue, causing the plants to become diseased. The fol- 

 lowing fungi, some of which attack living plants, can usually 

 be found : corn smut, wheat smut, soft rot of apple, brown rot 

 of peach or plum, mold on peaches, cherries, or improperly 

 preserved fruits, and mold on oranges or lemons. 



Object. To grow and study fungi. 



Materials. Stale wheat bread ; tumbler; microscope; slides 

 and cover glass ; other fungi obtainable, as corn smut, wheat 

 smut, or soft rot of apple. 



Directions, i. A typical fungus of bread mold may be 

 obtained in from three to five days. Moisten a small piece 

 of bread with water, place it in a large tumbler, and allow it to 

 stand exposed to the air in the room for an hour or two. Add 

 a few more tablespoonfuls of water and cover the tumbler with 

 a saucer or a piece of heavy cardboard. Keep this in a warm 

 room. Within a few days a white, threadlike growth known 

 as mycelium will develop. Mount a very small portion of this 

 in a drop of water on a slide, using a cover glass. Examine 

 this under the low and high power of the microscope. When 

 the spore cases appear make additional studies. 

 2. In a similar 

 Fig. 102. Corn smut manner collect and 



mount small bits 

 of the spore masses 

 (black dust) of 

 corn or wheat 



smut and examine them. Compare these black-dust spores 



with bread-mold spores for size. Compare various spores 



as to their color, shape, and size. Notice any particular 



markings on the walls of the smut spores and describe 



each of them. 



3. Place an apple, peach, plum, orange, or lemon which 



shows signs of a soft rot or decay in a dish and cover 



tightly for a day or two. A fungus will develop sufficiently 



to be easily seen with the unaided eye. Often diseased fruit 



with the fungus cropping out will be found hanging on the 



tree. Frequently diseased fruit or vegetables can be found 



in the grocery store. Examine small portions of any of 



the fungi which are cropping out from diseased fruit under 



the low and high power of the microscope, just as the 



bread mold was examined. 



[132] 



One of the best-known plant diseases. Common on 

 Indian corn all over the United States. The black 

 smut masses are composed of smut dust — a very 

 great number of spores. (Photograph by L. E. 

 Melchers) 



Fig. 103. Mold on orange 



This may easily be found on oranges and lemons in any 

 grocery store. If a small portion is scraped off with a 

 knife, mounted in water, and examined under the high 

 power of the microscope, the spores are easily seen. 

 (Photograph by L. E. Melchers) 



