248 GENERAL MORPHOLOGY OF PLANTS 



number of spores. In the great majority there are eight spores 

 in an ascus, while in some there are 16, 32, 64, 128, or even 6, 4, 

 2, and in a few i, or a variable number. These asci are usually 

 grouped together in extended surfaces or in conceptacles. These 

 make up the Class Ascomycetes. Here belong the cup fungi, 

 morels, black fungi, etc. 



401. Second. In the other class the characteristic fruit structure 

 is a short and specialized cell or hypha, which is single-celled, or 

 four-celled in the lower forms, and which bears on the outside 

 a definite and regular number of spores, usually four. This 

 specialized cell or hypha is called a basidium, which is the Latin 

 word for club, since this specialized cell is usually club-shaped. 

 These make up the Class Basidiomycetes. Here belong the smuts, 

 rusts, mushrooms, toadstools, bracket fungi, puff balls, etc. In 

 studying examples of the fungi it will be convenient to select them 

 from these three classes. 



ALGA-LIKE, OR SPORANGIUM-FRUIT FUNGI. 



(Class Phycomycetes.) 



The Conjugating Molds. 



402. The bread mold.* This fungus is very widely dis- 

 tributed over the world and grows on a great variety of 

 dead vegetable substances, and is, therefore, a saprophytic 

 fungus. It sometimes approaches the life habits of a parasite, 

 for it is often found causing a serious rot of stored vegetables, 

 especially sweet potatoes, beets, etc., when the storehouse or 

 cellar is not well ventilated and the temperature is too high. 

 It is called the bread mold, or black mold (Rhizopus nigricans], 

 because it often occurs on stale bread in close or damp places, in 

 age becoming black because of the dark spore masses and hyphae. 



* To THE TEACHER. If there is time for the practical study of only one 

 of the fungi of this class there is no better example than the bread mold. 

 The molds can be further illustrated by some examples of the white rust, the 

 downy mildews, etc., preserved on sheets, and of the water mold in culture. 

 Where more time is available for practical study these will serve as examples. 



