466 SYSTEMATIC BOTAKT. 



with the formation of the sclerotia, which consist of a dense mass ot 

 hyphse enclosed by a black rind. If the sclerotia germinate shortly after 

 their formation, the result is a mycelium which bears conidia again ; but 

 if germination is delayed for a month or two, a basin-shaped hymeniuiu 

 is formed, on which asci containing ascospores arise. This form of fructi- 

 fication is that commonly known as Peziza Fuckeliana. 



The spermatia borne in the spermogonia have, until lately, been believed 

 to be incapable of germination ; but M. Cornu states that he has caused 

 them to germinate and produce a mycelium like the conidia. In Peziza 

 and the allied genera the whole fructification is basin-shaped, with the 

 hymenium on the inner surface of the basin ; but in other cases, e. g. 

 Morchella, Helvetia, Spathularia, Geoglossum, &c., it takes the form of 

 clubs or stalked caps of considerable size with the hymenium on the outer 

 surface. Our present knowledge of the processes of fertilization, &c., in 

 the Discomycetes is the result of the labours chiefly of Tulasne, De 

 Bary, and Janczewsky. 



The species of Morchella and Helvetia are, as a rule, esculent, but none 

 of the other forms of Discomycetes have attained any reputation for this 

 quality. 



The genus Gymnoascus is an assemblage of small and very simple 

 Ascomycetous Fungi growing on dung. Its mycelium begets numerous 

 sexual organs, which, up to the time of fertilization, are (male and female) 

 exactly alike. After fertilization the carpogonium divides into a series 

 of cells, from which there grow out short, branched cells, on which the 

 asci containing 8 spores are borne in abundance. The fructification is 

 quite destitute of a covering. Though not agreeing with the general 

 characteristics of the Discomycetes, it is yet more nearly akin to them 

 than to any other forms of the Ascomycetes. 



Suborder 2. ERTSIPHE^E (fig. 1 B, p. 8.). Fungi growing on living 

 plants and dead organic bodies, and consisting of a mycelium which 

 spreads on the surface of the host and sends into it numerous 

 liaustoria ; forming small globular fruits with thin coverings, which 

 enclose one or several asci springing from a carpogonium. Illus- 

 trative Genera : Erysiplie, DC. ; Eurotium, Lk. 



Structure and Life-history. The species of Erysiphe grow on the 

 leaves and green stalks of Dicotyledons more rarely on Monocotyledons. 

 The mycelium ramifies densely on the surface of the host-plants, through 

 the epidermis of which it sends down numerous haustoria, and is repro- 

 duced by conidia produced in series at the end of unbranched conidio- 

 phores. As in many Ascomycetous and other Fungi, the conidia are the 

 only forms of reproductive organs known in certain species, and this has, 

 in the case of Erysiphe, as in the others, been productive of confusion of 

 genera. For example, Erysiphe Tuckeri, a vine disease, was long de- 

 scribed as a species of Oidium. On the other hand, in many other 

 species of Erysiphe, the sexually produced fructification is easily to be 

 found either adhering to the mycelium threads or free. Both conidia and 

 the sexually produced fruits are borne on the same mycelium. The car- 



