68 PLECTOMYCETES [CH. 



GYMNOASCACEAE : BIBLIOGRAPHY 



1880 ElDAM, E. Beitrag zur Kenntniss der Gymnoasceen. Cohn's Beitrage, iii, p. 267. 

 1903 Dale, E. Observations on the Gymnoascaceae. Ann. Bot. xvii, p. 571. 

 1907 DANGEARD, P. Recherches sur le developpement du peVithece chez les Ascomy- 

 cetes. Le Botaniste, x, pp. 86 and 97. 



A spcrgillaccae 



The Aspergillaceae are distinguished from the earlier families of the 

 Plectascales by the fact that their ascogenous filaments are surrounded by 

 a closely interwoven sheath of sterile hyphae so that a closed fruit or peri- 

 thecium is formed. In many species, the development of an ascus-fruit is 

 rare, and reproduction depends on the abundant and very efficient conidia; 

 in others, which, judging by the form of their conidial fructification, should 

 belong to this family, ascocarps are unknown. 



The species occur either saprophytically or parasitically upon a wide 

 variety of substrata. Many of the saprophytic forms, including species of 

 Eurotium and Penicillium, grow with especial readiness on fatty substances, 

 Emericella erythrospora occurs on olives, and Monascus Iietcrosporus on 

 glycerine or tallow. 



Several species. of Penicillium together with other fungi and bacteria 

 are concerned in the "ripening" of cheese, on the proteids of which they 

 act by means of a proteolytic enzyme. 



The species of Microascus, Aphdnoascus and some others are coprophilous, 

 and several members of the family occur on wood. 



The parasitic forms are less numerous; various species of Penicillium 

 and Eurotium are pathogenic on man and animals, and some, if they obtain 

 entrance through a wound or other aperture, are the cause of ripe rot in fruit. 



Thielavia basicola, the only member of the family which causes an 

 important plant disease, is sometimes separated from the Aspergillaceae 

 and classed with the Perisporiaceae. This species infects the roots of tobacco 

 and certain other plants, and in the early stages multiplies by means of 

 hyaline conidia (endospores) produced inside mycelial branches, from the 

 ends of which they are afterwards expelled, givingthe infected root a mildewed 

 appearance. Later, thick-walled brown chlamydospores are differentiated 

 in rows at the ends of hyaline filaments so that the root is covered with 

 a dark coating. Normal development of the root is prevented and the host 

 killed or stunted ; if recovery does not take place perithecia are developed 

 on the dead plant. 



The formation of the perithecium in most investigated species is initiated 

 by the appearance of sexual organs, from the stalks of which the cells of the 

 sheath arise. In Microascus and in Emericella the sheath opens by a pore, 

 but in the majority of cases it remains closed, and the ascospores are finally 



