J 220 



water. In garden soil (Hilium is generally spread as maj' be shown 

 by inoculating feebly acidified malt infusion with soil and keeping- 

 it at 25° to 30^ C. The lilm which finally covers the liquid contains 

 besides Mycoderina, always Olilluni. Pressed yeast, long whey, sour 

 milk, cheese, the output waters of distilleries and all kinds of acid 

 sewage, are iidiabited by Oidiinn. Natural hal)itats ai-e furthermoi-e 

 the sap flow of many trees caused by Cossiis lujniperdd and allies. 



For pure culture acidified malt infusion- or broth-glycerin |)lates 

 are recommendable. The acid serves to exclude the hay bacteria 

 which have a great disposition to grow in symbiosis with Old'niia 

 in neutral environment. 



The transfers for the collection are kept on malt-agar, but they 

 change thereby in a few months into a tough, leathery mycelium, 

 almost exclusively consisting of long mycelial thieads difHicidt to 

 separate and evenly to mix with the nutriment. To obtain normal 

 material in this case a new isolation from milk or soil is necessary, 

 for the change is an hereditary non-reversible niulation. 



Under favourable feeding conditions the giowtli is remaikablj- 

 rai)id and the respiration and oxygen absorption go parallel with it. 

 This intensity exceeds by far that of the ordinary moulds of the 

 genera PenicilUuia and Aspen/t/hts, whilst it equals that of Mucor. 

 This holds, however, only good with regard to easily assimilable 

 substances; less decomposable matter such as pectine, cellulose and 

 chitine are not attacked by Oidium. Gelatin and agar are neither 

 assimilated. Fermentation phenomena, joined with the evolution of 

 gas, are as said also wanting. Hence, (Jidium never forms rents or 

 holes in the solid substrata whei-ein it is cultivated, not even in presence 

 of glucose. This is one of the reasons why it is so well adapted to 

 the culture experiments with the anaerobes to be discussed below. 



The products of metabolism are chiefly or oidy water and carbonic 

 acid ; volatile or non-\ olatile substances noxious to other organisms 

 are not produced. 



In regard to carbon-food Oidium. exhibits a great specialisation. 

 Most hexoses, in particular glucose, levulose and mannose, are 

 readily assimilated and oxidised. Likewise aethylalcohol. Glycerin, 

 too, is a very good carbon source. On the other hand, starch, 

 raffinose, maltose, cane sugar, mannite and all similar substances, 

 are in no way assimilated. Enzymes, as diastase, maltoglucase, in- 

 vertase, lactase, are hence completely absent. Glucoside enzymes 

 could neither be found. By the absence of these enzymes, Oidium, 

 which so easily reads on the hexoses, is especially fit as. a 

 reagent on these enzymes in case they are to be detected in parts 



