WHITE MILDEWS OR BLIGHTS. 177 



occurring on straw, the most common one is figured, 

 natural size, in our plate (fig. 257) ; but from this 

 no idea can be formed of its structure, which in 

 some points resembles an Erysiphe. The concep- 

 tacles are thin and brittle, and are clothed ex- 

 ternally with long dark-coloured branched hairs 

 (figs. 258, 259). The conceptacle contains long 

 narrow sporangia, each enclosing dark, almost 

 black, lemon-shaped sporidia. For low powers 

 this is a very interesting object. The minute struc- 

 ture affords no feature of popular interest. This 

 fungus (which bears the name of Chcetomium 

 elatum) is common on old straw, thatch, reeds, 

 matting, &c, resembling small brown tufts of hair, 

 visible to the naked eye. 



Paper much exposed to damp will occasionally 

 develop a similar " bristle-mould," surrounded by 

 a yellowish spot (Ohcetomium chartarum, Ehrb.); 

 but it is not so common as the last. In habit 

 and structure it is very similar (figs. 252, 253). 



In 1838, the Rev. M. J. Berkeley announced the 

 discovery by him of a singular production, for 

 which he was unable to find a fitting location in 

 any genus then established, and for which he accord- 

 ingly characterized a new one, under the name 

 of Ascotricha. This new species of paper mildew 

 was found by him on some printed paper in a box. 

 It somewhat resembles the other species above 

 alluded to, at a casual glance ; but more minute 

 examination will reveal its differences. The author 



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