Lecture on the Parasitic Fungi of the British Farm. 391 



I have not time to dwell on other kindred fungi found occa- 

 sionally on the gramineous tribes. All are more or less subject 

 to some uredo peculiar to them. 



(8.) I may be expected to allude to the true theory of fairy 

 rings, which are due to three species of the most highly organized 

 fungi, called agarics. Mushrooms are agarics. Those of the 

 fairy rings throw out their spawn in a circular direction, and the 

 ground being continually exhausted by it, a ring is formed, which 

 is rendered greener than the surrounding grass by the stimulus 

 of the spawn itself. 



I may just observe that in some countries, grasses and corn, 

 and particularly barley and rye, are destroyed by a curious mould, 

 which is developed beneath the snow, and if it appears in snow 

 without previous frost, it is often fatal to the whole crop. It has 

 not yet been noticed in Great Britain, but the matter will be 

 worthy of attention should any long frost occur. 



I cannot omit to state here that the mouldiness in stacked hay is 

 generally the common aspergill, to be described presently, and some- 

 times the common penicillium, also coming under review. The scores 

 of these will be seen to be injurious, and therefore such hay ought 

 always to be steamed. The cut surface of hay-stalks is sometimes 

 covered with a light orange or brick-dust red fungus, which is a 

 fusarium, so termed from the spindle shape of the spores, but it is 

 entirely confined to the section of the stems composing the hay. 



II. I go on next to the parasitic fungi of leguminous plants, 

 which are particularly subject to them. A small dipazea destroys 

 peas in wet seasons, attacking all parts, especially the pods ; but 

 the blight which we mostly see on peas, bears the botanical name 

 erysibe, or erysiphe, the Greek for mildew, and is the same kind of 

 mould that infests peach-leaves. In its early stage it is a jointed 

 mould, seemingly superficial, which on examination shows little 

 globules, changing from yellow to black, and springing from a 

 flocose web, filled with minute sacs containing the sporules. (See 

 Fig. 12.) These globules, and the sacs containing the spores, are 



Fig. 12. Erysiphe highly magnified. 



2 D 2 



