HYPHOMYCETES 397 



The species are mostly minute, and come under the 

 designation of microscopic fungi, and are popularly known 

 as * moulds/ although this term is somewhat vague, and is 

 also used for certain members of the Phycomycetes, as 

 Mucor, etc. 



Most species are gregarious, and form white or coloured, 

 cottony or velvety patches, on decaying or dead plants, 

 insects, etc. ; some species, however, are destructive para- 

 sites. In some species the conidia are borne singly at the 

 tips of hyphae, in others clusters of conidia are produced, 

 and in a few species the heads of conidia are involved in 

 mucus, and thus superficially resemble the heads of 

 Mucor, where the conidia are contained within a cell or 

 sporangium. 



When mature the conidia fall away from the conidio- 

 phore very readily, and are distributed by wind, insects, 

 birds, etc. If placed in water for examination the conidia 

 separate from the conidiophore at once, so that their mode 

 of attachment cannot be observed, but if placed in glacial 

 acetic acid they remain attached, and can then be stained 

 and mounted in balsam or other media. 



KEY TO THE FAMILIES 



Hyphae pallid or brightly coloured, flaccid or collapsing, 

 and not cohering to form a compound, stem-like structure ; 

 conidia hyaline or clear coloured. Mucedineae. 



Hyphae dark coloured, brown, olive, or blackish, rather 

 rigid, often crowded, but not fasciculate, rarely almost 

 hyaline, but in that case the conidia are dark coloured. 



Dematieae. 



