MOULDS. 159 



its power and limited its miscMef. Mouldy vetches 

 and mouldy peas are, especially in moist seasons, 

 evils to which the agriculturist knows his crops to 

 be subject; he may not know, however, that this 

 kind of mould (fig. 266) is of so near a kin to that 

 which has acquired such wide-spread fame in con- 

 nection with the potato. Another species of fungus 

 attacks the garden pea in damp seasons, forming 

 small depressed brownish spots on the leaves and 

 pods ; but this is quite distinct from the mould, 

 though probably not less injurious. 



The fertile threads are produced in dense clusters, 

 each many times branched, and bearing elliptic 

 acrospores obtuse at their apices, and of a violaceous 

 tint (fig. 266). The oospores are beautifully reti- 

 culated and of a yellowish-brown colour (plate X. 

 fig. 212). 



Trefoil and some other alHed plants are attacked 

 by another species, characterized by Dr. de Bary as 

 Peronospora trifoliorum, which we have found rather 

 plentifully in some localities on lucern. 



The Paesnip Mould [Peronospora niveaj Ung.) 

 is found on many umbelliferous plants; but its 

 attacks upon the parsnip are most to be deplored, 

 because it injures and ultimately destroys an ar- 

 ticle of human food. The plants infested with this 

 parasite are first attacked in the leaves, but after- 

 wards the roots become spotted and diseased in a 

 similar manner to the potatoes attacked by its 

 congener. The disease has not hitherto been so 



