YEASTS AND MOLDS 299 



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. 



Peptone i gm. 



Maltose 4 g m - 



Agar 1.5 gm. 



Water . 100 cc. 



FIG. 74. Actinomyces bovis. Showing the hyphal structure of this pathogenic 

 fungus. There are numerous fungi of the mold 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 mold 

 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 mold. The acid reaction of the me- 

 dium (+2) will, however, usually prevent bacterial growth. 



Yeast organisms may be studied very conveniently in the hanging 

 drop. The development of' mould may be observed between two sterile 

 slides. Since these organisms are much larger than bacteria there is little 



