382 MYCOSPELERELLACE^. 



noticeable by their power of refracting light and consequent lustre. 

 In fact, this peculiarity renders the drops of oil liable to be 

 confounded with endogenous spores a point on which warnings 

 have been issued by E. LAURENT (VII.) and afterwards by 

 0. SETTER (I.). This was also probably the cause of the mistaken 

 opinion formed by JOHANOLSEN (I.), whose error was corrected 

 by ALB. KLOCKER and H. SCHIONNING (IV.). In some cases the 

 gemma? subsequently develop a longitudinal septum, due to the 

 transverse division of the mycelial cells. At a still later period 

 the external layers of the thick cell wall sometimes become 

 mucinous to such an extent as to render the nutrient liquid 

 viscous (see vol. i. p. 285). In this manner a culture of Dematium 

 pullulans (grown, for instance, in beer wort) will develop into a 

 greenish brown to dark green, thin, but viscous, film, resembling 

 paper, on the surface of the liquid, whilst a deposit of yeast-like 

 conidia and conidial cultures collects at the bottom. 



According as the gemmae are well nourished or the reverse, 

 they either develop into a mycelium from which lateral buds are 

 separated by constriction, or they produce these buds direct. 



Dematium pullulans also affords an example of the cell fusion 

 already referred to on p. 6, vol. ii., by the coalescence of two 

 adjoining cells of the same mycelium, one of them penetrating the 

 other. In Dematium pullulans more particularly which, as 

 already stated, exhibits a marked tendency to the formation of 

 budding cells by constriction there gradually develops, within 

 the invaded cell, or host, a varying number of approximately 

 ellipsoidal cells, which are in turn capable of reproduction by 

 budding. In this way, under favourable conditions, a filament 

 may become filled with cells which an observer unfamiliar with 

 its method of origin may readily mistake for an ascospore (see 

 Fig. 189). Such an erroneous impression has already been 

 produced in the minds of several workers : for instance, 0. JOHAN- 

 OLSEN (I.) in the case of a fungus he named Dematium casei, and 

 also Alfr. Jb'rgensen and FR. WELEMINSKY (I.) with Dematium 

 pullulans itself. We are indebted to A. KLOCKER and H. SCHION- 

 NING (IV. and VII.) for the correct interpretation of the pheno- 

 menon. This correction destroys the corresponding erroneous 

 classification of Dematium pullulans with the group of the 

 Exoascece or similar low Ascomycetes. 



As a result of its frequent occurrence on straw, and therefore 

 in the atmospheric dust in cowsheds, Dematium pullulans is likely 

 to be often found in milk ; and it has actually been detected in 

 that liquid on many occasions by ADAMETZ (III. and IV.). When 

 the milk is curdled, a larger or smaller proportion of the fungus 

 content passes into the curd. Its mode of action in this case 

 requires elucidation, and an attempt to explain it was made by 

 O. JOHAN-OLSEN (I.). This worker discovered in Norwegian 

 " gammelost " (see p. 85, vol. ii.), a hyphomyces which he termed 



