OIDICJM LACTIS AND ALLIED SPECIES. 455 



whose divergences are most clearly apparent in cultures on 

 potatoes and casein. 



Oidium lupuli, Matthews and Lott, is occasionally observed, 

 as a reddish dust, on hops that have been stored damp, the dust 

 consisting of the conidia of this fungus. In artificial cultures 

 according to LINDNER (XLI.) it forms a quick-growing superficial 

 mycelium, the richly branched aerial hyphse of which fall apart as 

 oidia (Fig. 207). They are mostly oval, swelling up to a nearly 

 globular shape before germinating. The colour is red at first, 

 afterwards turning yellow. 



P. LINDER (XL.) also assigns to the genus Oidium a fungus 

 discovered in samples drawn from the storage casks at the Berlin ex- 

 perimental brewery and occupying a morphological position between 

 Oidium and Sctccharomyces. This species Oidium pullulans, Lind- 

 ner (see Fig. 208) not only exhibits the oidium-like disintegration 

 of the mycelial filaments, but also budding growths resembling yeast 

 cells. In some small-drop cultures these yeast cells are formed 

 exclusively, without any tendency to septation of the hypha3, but 

 in other cases there is an abundant formation of mycelial threads 

 with budding cells. On wort it quickly forms a thin film with a 

 strong ring ; and on wort gelatin, yellow-brown colonies, resem- 

 bling those of yeast and with a dull lustre. Lindner did not 

 succeed in observing any fermentation. The close relationship of 

 this fungus to Monilia is unmistakable, and it would probably 

 be advisable to include it in that category. 



