CHAPTER XXL 

 FUNGI: THE BLACK MOULD. 



Demonstration 32. 



211. To grow the mould. — This plant maybe grown byplacing old bread, 

 or partly decaying fruits, as bananas, or the peelings of lemons or oranges 

 in a moist chamber. Set this in a warm place for about one week. Then 

 the plant may be grown on potatoes as described in paragraph 49, or one 

 may take the material for study directly from the bread. It should be 

 studied before it becomes very old. 



Exercise 44. 



212. Mycelium. — Before the black heads of the fungus appear, note the 

 delicate fluffy white tufts of threads which appear on the surface of the bread 

 or other substance on which the fungus is growing. These threads are the 

 mycelium, and a single thread is a mycelium thread, or " hypha." 



Search on the margins of old cultures where the threads come in contact 

 with paper (some sheets of paper should be placed by the sides of the cul- 

 tures) or the sides of the vessels for " runners," long threads of mycelium 

 which touch the place of support here and there. Are there tufts of upright 

 threads at the points of contact which bear black heads ? Try to find the 

 connection of the black threads with the creeping mycelium. 



If the mycelium has not been studied in a previous chapter the teacher 

 can mount some here for demonstration. Let the pupils note the branched, 

 colorless threads, and that there are no cross-walls. Note the granular 

 protoplasm. 



At the microscope let each pupil note the long dark-colored stalks which 

 bear the rounded "heads" ; the latter are the sporangia. If the spores are 

 mature the sporangium wall is perhaps broken and the spores more or less 

 scattered. If so, note the remnant of the wall as a small collar below the 

 enlarged end of the stalk. The enlarged end of the stalk is the ' ' colu- 

 mella." In the younger stages of the sporangium, note the columella 

 arched up within the sporangium. Trace the stalks down to their attach. 



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