116 CLASSIFICATION OF THE MICRO-ORGANISMS. 



the numerous fruit hyphae grow, clothe the stiff mummy- 

 like corpse with a snow-white mould, and bear on their sides 

 several spore capsules, with colourless spherical spores. The : 

 latter germinate in various nutrient solutions, and are thus 

 capable of artificial cultivation. 



iiust fungi. 5. Uredineae, or ^EcidiaceaB (order: Basidiosporece) . 

 Parasites on plants. The thread-like mycelium grows 

 between the cells of the plant which acts as host, and the 

 organs of fructification which arise under the epidermis 

 burst through it in the form of small, often reddish 

 dust-like masses or patches, which consist of closely 

 packed basidia. In most cases there is well-marked 

 alternation of generation ; formerly the different fructi- 

 fying forms were described as distinct species of fungi 

 uredo, puccinia, recidium while at the present time 

 these former specific names are only used for the 

 particular spore form of these species of fungi. 



As an example we may mention Puccinia graminis,ihe rust 

 of grain, which occurs on many grasses. It forms on its 

 mycelium, which grows under the epidermis of the plant, club- 

 shaped masses of basidia, which give rise to spores by segmen- 

 tation, break through the epidermis, and set free the spores 

 in the form of oval cells, in whose protoplasm an orange red 

 oil is present, and whose episporium is colourless and rough. 

 These spores, the so-called uredospores, or summer spores, 

 sprout rapidly, and develop always the same mycelium and 

 the same fructification during the whole summer. In the 

 autumn, however, club- shaped spore cells develop on the 

 basidia, which consist of two superimposed cells with thick, 

 dark brown membranes, smooth 011 the outside; these so- 

 called telcutospores, or winter spores, germinate in the 

 following spring, but the germinating tube does not penetrate 

 into a plant, but sends out only a few thin branches, at the 

 end of which roundish, colourless cells are formed by segmen- 

 tation. The sporidia so formed germinate quickly, not on 

 grasses, but on the leaves of the barberry bush, through the 

 epidermis of which the germinating tubes of the sporidia 

 penetrate. The thallus developed in the barberry is called 

 ^Ecidium bcrberidis ; from it short basidia are developed in 

 flask-shaped organs (ajcidium flasks, the covering of which 

 is called peridia), and burst through the epidermis on the 

 under surface of the leaves. On the basidia long rows of 

 simple roundish cells are formed, containing reddish-yellow oil 

 drops. The BBcidinm spores germinate as soon as they arc 



