chapti:r xxix. 



EU-MYCETES.— (^) BASIDIOMYCETKS. 



The Basidiomycetes form the second sub-class of tlie septate Ku- 

 mycetes. They inckide most of the large Fungi, such as the 

 Mushrooms, Toad-stools, Shelf-Fungi, and Puff- Halls. These arc 

 almost all saprophytes. But the Basidio- 

 mycetes also include the Rusts and Smuts, 

 which are parasitic forms causing disease. 

 Some of these are the most injurious pests 

 to cereal crops, such as the Rust of Wheat, 

 or the Smut of Oats. Some Basidiomycetes 

 also take part in the formation of certain 

 types of Lichens. They are thus very 

 varied in their habit, and include many 

 familiar objects. The characteristic feature 

 is the Basidium, which takes a place in the 

 life-cycle corresponding to the ascus in 

 the Ascomycetes ; for in both of them 

 there is nuclear reduction, and both pro- 

 duce post-sexual Carpospores. But while 

 in the ascus they are formed internally 

 'Fig. 362, p. 429), in the basidiuni they 

 ire borne externally (Fig. 374). 



In the Basidiomycetes normal sexuality has not l>ecn shown to exist, 'u-hilc 

 It is only in the Uredineae or Rusts that organs are found which. thouRh no 

 longer functional as such, are held to be of the nature of sexual organs. Thi« 

 would indicate that the Uredineae are relatively primitive types of the 

 Basidiomycetes. It may be held as probable that all tlicsc FunRi were dcrix-r.! 

 from a sexually reproducing ancestry ; but that the sexuahtv is m .i»- 

 in the more advanced parasites and saprophytes, while vrstiijcs «.f it j. 

 in the more primitive Rusts. 



441 



1 10. J74 

 Honey A)fari<- (ArmtiUrtM muUjm). 



A, younp ' ' ' 



iiuclii. J 



nuclfi. ' 



appenJu . 



(k-rivcd ; 



<.( the I .. 



four basi<ii-p ». -i ■* 



iukIpus into tli- (Allcf 



Kuhland ) (l-i f> 



