THALLOPHYTA. 



685 



is a further justification for the inclusion of all these families at first sight so 

 different in a single alliance. 



Uredinece. These are the Rust-fungi, parasites for the most part on the foliage 

 of higher plants. They are outwardly manifest in the form of yellow or brown 



Fig. 390. Basidiomycetes. 



1 Clavaria aurea. 2 Dcedalia quercina. *Marasmius tenerrimus. < 31 arasmius perforans. * Craterellus clavatus. *Amanita 

 phalloides. 1 A portion of the basidial layer of the last-named Fungus showing the sterigmata and conidia. Hydnum 

 imbricatum. Polyporus perennis. "> x 250 ; the rest nat. size. 



spots and streaks, due to the spores, which are formed in masses on the surface. 

 The mycelium inhabits the intercellular system of the host-plant, and draws its 

 nourishment from the living cells. The spores are regarded as chlamydospores, that 

 is to say, localized, thick-walled segments of the hyphaa having the properties of 

 reproductive cells. These spores are met with in three forms in the Uredineae. The 



