158 MYCOLOGY 



to remove the air, washed and mounted permanently stained, or 

 unstained in acetic acid with a ring of asphalt, or in glycerine jelly 

 for a study of the asci and ascospores. For a study of the distribution 

 of the haustoria and for a detailed examination of the sexual organs,^ 

 small pieces (2 by 4 qcmm.) of hop leaves on which myceha of the 

 mildew (Sphcerotheca) are found in various stages of development 

 should be fixed in weaker Flemming's solution, as described by Zim- 

 mermann on page 178 of his "Botanical Microtechnique," and then 

 hardened in alcohol and carried through to paraffin. The sections 

 should be cut 5 to 7.5^ thick stained with safranin (one to one and 

 one-half hours), gentian-violet (one-half to one hour), and orange 

 G. (quickly), then treated with absolute alcohol, cleared in oil of cloves 

 and mounted in balsam. 



The material for systematic study should be handed to members of 

 the class in mycology, mounted and then studied as unknowns by the use 

 of the generic and specific keys given in Appendix VIll, pages 721-726. 



Family 2. Perisporiace^. — The aerial mycelium of these fungi 

 is superficial black, filamentous, or wanting, or rarely as a firm stroma. 

 The perithecia are situated on the aerial myceUum, or on the stroma. 

 They are black, + spheric, rarely elongated, poreless, or weathering ir- 

 regularly at the apex and without appendages. The wall is mostly 

 membranous, or brittle. The asci are clustered and mostly elongated. 

 The shapes of the spores are various. Paraphyses are usually wanting, 

 and are present in only a few cases. 



The genus Scorias has been described incidentally in a foregoing page 

 (72). It is represented in America by a single species, spongiosa, ^h.\c\\ 

 lives on beech twigs and leaves associated with some species of wooly 

 aphis, or on the ground where the droppings of the aphis in the form 

 of honey-dew have collected. Its mycelium is greenish-black, much- 

 branched, rigid, septate and the hyphae are glued together by an 

 abundant mucilaginous substance forming a loose spongy mass, bearing 

 an abundance of pyriform, coriaceous perithecia, which enclose narrow, 

 thick-walled, eight-spored asci. Elongate pycnidia and perithecia are 

 also frequently seen. 



Family 3. Microthyriace^. — The mycelium of the fungi of this 

 family is superficial and dark in color. The perithecia are superficial 



1 Harper, R. A.: Die Entwickelung des Peritheciums bei Sphcerotheca Castagnei, 

 Bericht. der Deutsch. Bot. Gesellsch., xiii, Heft. 10: 475-481, 1895. 



