FUNGI 



391 



is a sac in which spores are borne. (See Figure 186.) The 

 asci are not always inclosed in a case as in lilac mildew; 

 in other ascomycetes they form the Uning of cup- or fun- 

 nel-shaped structures. The hyphss: of this group have 

 cross walls. Some of them are known to reproduce sexu- 

 ally, but the sex organs are not like those of algae. 



(3) Basidiomycetes. — The word means basidium fungi. 

 You have learned what a basidium is in connection with 

 toadstools, and also in connection with wheat rust. Both 

 of these forms are basidiomycetes. Any forms in whose 

 life history basidia appear are put in this group. The 

 hyphae have no cross walls, and no sex organs have been 

 discovered. 



E. Fungi and the Soil. — The importance of bacteria 

 in rendering the soil fertile was described a few pages back. 

 Some of the true fungi are also important in connection 

 with this subject. 



Soil is a very complex thing. Except where it is quite 

 bare of plants, like bare sand, it contains more or less of 

 organic material. This organic material comes principally 

 from the bodies of plants which have lived and died in 

 and upon the soil. This organic material is food for fungi, 

 for true fungi as well as bacteria. Rich soil, Hke stagnant 

 water, is full of invisible life, and this invisible life affects 

 the visible plants which grow from such soil. Humus is 

 filled with fungi. They are as much a part of the soil of 

 the forest as the rotting branches and the decaying leaves. 

 This hidden life in the soil is not well understood, but we 

 do know that the fungi, which principally compose this 

 soil life, produce certain changes which are beneficial to 

 green plants, 



