EU-MYCETES.— (^;) BASIDIOMYCETES 



4SI 



important is the prevention of the manure being contaminated by 

 the carposporcs from the smutted crop of a previous year. 



Hymenomycetes. 



The Life-History of the Rust of Wheat has been described in some 

 detail as giving an example of a Basidiomycctc which still " 

 evidence of sexuality, both morphologically and physiolo;'; 





I'IG. 356. 



Polyporiis igniarius. Section through an old fructihcation, showing annual zones 

 of growth. a=point of attachment upon the tree which is its host. I^e pjfous 

 hymenium is directed downwards, (i nat. size.) (l-rom Strasburfjcr.) 



though it is altered from what was probably its normal and original 

 course. In the rest of the Basidiomycetes such evidence is wanting. 

 They may provisionally be held to be saprophytes and parasites 

 which were descended from an ancestry 

 with normal sexuality, but have ad- 

 vanced further in the elimination of 

 their sexual process. The Basidio- 

 mycetes are characterised by their 

 basidia (Fig. 374, p. 441) borne on 

 friiit-bodies which are often large, of 

 various form and brightly coloured. 

 These are produced upon a myceliuin, 

 which acquires the necessary nourish- 

 ment sometimes parasitically, but 

 more commonly from saprophytic 

 sources. The basidia arc borne in 

 various ways, and this gives distinctive room, n 



-^ ' ^ of the r.i 



characters to the main groups of To the 



these Fungi. Thus in the Gastero- 



mycetes the fructification is closed, the basidia bcin-; pr...];;. , ; ::i:. : 



nally, and the spores set free by rupture, as in the PulT-B.ilh. In the 



Hymenomycetes the basidia arc borne collectively in a definite layer 



Fio. 387- 



