DEMATIUM PULLULANS. 381 



this question could be finally settled would be by inducing the 

 llypliomyces to develop perithecia, which no one has yet succeeded 

 in doing. However, for the present, Dematium pullulans may be 

 classed as a (still undetermined) species allied to Sphcerulina 

 intermixta, even if it cannot be regarded as forming part of the 

 morphological cycle of the latter. The identification of species in 

 this group is still in a very defective condition. The morpho- 

 logical similarity is very great, not only between Dematium 

 pullulans and the conidial fructification of Sphcvrulina intermixta, 

 but also between both and the conidial fructifications of the 

 Dothidea ribesia and D. puccinioides described by Brefeld, the 

 Fumayo salicina examined by ZOPF (XT.) forming the chief 

 constituent of true smut Cladosporium herbarum, and others. 

 Undoubtedly, however, Dematium pullulans stands nearest to 

 Sphcerulina intermixta, and its consideration in this place is 

 therefore justified. On its account alone has mention been made 

 of the said Ascomycetes, the ascospores of which, on the other 

 hand, are developed only outside liquids, and possess little interest 

 to the fermentation physiologist beyond the developmental history 

 sketched above. The views of earlier workers, who sought to 

 establish a connection between Dematium and the true yeasts (see 

 pp. 107, 108, vol. ii.) are entirely erroneous. 



Consequently, the form known as Dematium pullulans alone 

 constitutes the subject of the following lines. For exhaustive 

 investigations into its structure we are more particularly indebted 

 to E. LOEW (V.). 



If one of the yeast-like buds (conidia) of Dematium pullulans 

 be placed in a suitable environment, it grows to an extensive 

 mycelium, the several members of which throw up numerous 

 ellipsoidal conidia in turn. According to the researches of W. 

 SCHOSTAKOWITSCH (I.) on the influence of external conditions on 

 the formation of the budding cells (see pp. 21, 22, vol. ii.), however, 

 these conidia are not produced when the mycelium is made to 

 grow in a strong solution of grape sugar or saccharose. The limit 

 in this respect was determined by O. VON SKERST (I.) as about 

 50 per cent. A temperature of 3o-3i C. has a similar restric- 

 tive influence; though by gradual habituation to progressively 

 increasing temperatures it is possible to obtain at last a culture 

 the mycelium of which will produce conidia at 30 C. At 

 5o-55 C., however, the mycelium is killed, after an exposure 

 varying with its age. 



On air being freely admitted to the nutrient solution, the 

 hitherto slender, colourless cells of the mycelium are transformed 

 into short, protuberant forms (gemmae, see p. 24, vol. ii.), the 

 membrane of which thickens and acquires an olive-green to brown 

 tone. The depth of this colour depends, according to 0. VON 

 SKERST (I.), on the richness of the nutrient solution, and increases 

 therewith. At the same time an abundance of fat collects in the 

 colls in the form of drops, which increase in size and are rendered 



