FUNGI. 239 



the structure is the same, the orighi the same, and the 

 life-history, with very little variation. There is still 

 one mystery connected with this genus of fungi, on 

 which no light has hitherto been thrown. All the 

 species, in whatever country they may be found, are 

 comparatively rare, and it seems scarcely possible to 

 guess by what means each species is perpetuated. 

 It may be true that each perfect club can develop 

 myriads of spore-bodies, but by what means these are 

 disseminated, and how they find a lodgement in the 

 bodies of healthy insects, is as yet an unsolved 

 problem. 



Fly Moulds. 



It is not difficult to impart a superficial idea of 

 what we intend by the term " fly moulds " by calling 

 attention to a very common and well-known example 

 which occurs in the case of the house-fly in the 

 autumn. Especially after moist and oppressive days, 

 flies will often be observed fixed to the window- 

 pane or looking-glasses, as well as other smooth and 

 polished surfaces, by their extended feet, the insects 

 being quite dead, surrounded by a kind of frosty halo 

 resembling a minute snowy-white dust. This frosty 

 appearance extends also to the body of the im- 

 molated fly which has fallen a victim to the fly- 

 mould, Einpiisa nuisccB. It is not so very many 

 years since this disease, to which it was then known 

 that flies were subject, was considered to be the only 

 one of its kind, but now some scores are recognized, 

 and all due to the invasion of a parasitic fungus. It 

 was then believed, and even now affirmed by a few 



