YEASTS AND MOULDS. 



147 



Moulds differ from bacteria in that they thrive best in acid media and in 

 that they are not so readily killed by means of the usual chemical disinfec- 

 tants. Heat (dry as well as moist) kills the hyphal structure quite readily, 

 but the spores are quite resisting, though less so than the spores of bacteria. 

 They can be cultured on potato, on bread, or on other organic food materials 

 (kept moist in a moist chamber) . The following medium is very satisfactory. 



Maltase 4 gm. 



Peptone i gm. 



Agar 1.5 gm. 



Water . 100 c.c. 



FIG. 68. Actinomyces bovis. Showing the hyphal structure of this pathogenic fungus. 

 There are numerous fungi of the mould group that cause local pathologic conditions of the 

 skin and mucous membranes. 



Mix, dissolve, filter, titrate to reaction + 2 and sterilize in the usual way. 

 Culturing is usually done in Erlenmeyer flasks (250 or 500 c.c.) with a thin 

 layer of the medium in the bottom. Before placing the mould material 

 in the flask (by means of a platinum loop) allow it to macerate in 60 per cent, 

 alcohol for two hours which will kill the bacteria present without destroying 

 the life of the mould. The acid reaction of the medium (+2) will, however, 

 usually prevent bacterial growth. 



