9 o PLECTOMYCETES [ch. 



1912 FOEX, M. Les conidiophores des Erysiphace'es. Rev. Ge"n. Bot. xxiv, p. 200. 



1913 Salmon, E. S. Spraying Experiments against the American Gooseberry Mildew, 

 Journ. S. E. Ag. Col. xxii, p. 404. 



1913 Salmon, E. S. Observations on the Life-History of the American Gooseberry 

 Mildew, Journ. S. E. Ag. Col. xxii, p. 433. 



1913 Salmon, E. S. Observations on the Perithecial Stage of the American Gooseberry 

 Mildew, Journ. S. E. Ag. Col. xxii, p. 440. 



1914 BezssonOFF, M. N. Sur quelques faits relatifs a la formation du pe"rithece et la 

 delimitation des ascospores chez les Erysiphaceae. Comptes Rendus Ac. Sci. clviii, 

 p. 1 123. 



Pcrispo riaceae 



The Perisporiaceae include about three hundred species, many of which 

 are but little known, while none have been cytologically investigated. They 

 develop as epiphytes on the leaves or young parts of plants, or occur on 

 decaying plant substances. They usually possess a dark-coloured filamentous 

 mycelium, but this sometimes forms a firm stroma, or again may be altogether 

 lacking. The perithecia are superficial, dark in colour, and usually more or 

 less spherical ; they are typically without appendages, but mycelial out- 

 growths from their base may simulate these structures as in Meliola. The 

 wall of the perithecium is generally membranous, more rarely carbonaceous 

 and brittle; as a rule there is no definite opening but sometimes an irregular 

 rent is formed at the apex {Antennaria), and sometimes the perithecium 

 opens by valves {Capnodium). The asci are elongated and more or less 

 cylindrical and the spores have one or more septa and are sometimes 

 muriform; paraphyses are not generally developed. 



Dimerosporium, the largest genus with some sixty species, is epiphytic on 

 the leaves of angiosperms,and one species (D. Collinsii) forms vvitches'-brooms 

 on the service-berry. The mycelium is dark-brown, the spores two-celled. 



The species of Capnodium, Apiosporium and Meliola, are among the soot 

 fungi, which form a black coating on leaves. They are purely epiphytic and 

 saprophytic, subsisting on the honey dew secreted by insects, and doing little 

 damage, as they are seldom thick enough to interfere with the supply of light. 



In several species a considerable variety of accessory fructifications are 

 produced. Thus Meliola Penzigi, the "sooty-mould" of the orange, has 

 conidia which differ little from the vegetative cells, multi-cellular conidia, 

 conidia borne in small spherical pyenidia, and conidia abstricted from 

 conidiophores in pustules or conceptacles, which may be flask-shaped or 

 variously branched ; some of these accessory spores are developed in great 

 abundance and perithecia are relatively rare. 



PERISPORIACEAE: BIBLIOGRAPHY 

 1897 Webber, H.J. Sooty Mould of the Orange and its Treatment. U.S. Dept. Ag. Veg. 



Phys. and Path. Bull. 13. 

 1892 Ellis, J. B. and Everhart, B. M. North American Pyrenomycetes. Ellis and 

 Everhart, New Jersey. 



