60 LABORATORY GUIDE IN BACTERIOLOGY 



Granulation. 

 Outgrowths. 

 Coloration of medium. 

 Cloudiness. 

 Gas-formation. 

 V. Stab-culture in glucose-agar. 



Describe like plain agar, and in addition always 

 note presence or absence of gas-formation, and 

 presence of cloudiness. 

 VI. Stab-culture in gelatin. 



Describe like plain agar, and in addition always 

 note presence or absence of liquefaction. If 

 liquefaction is present, it may be saucer-shaped, 

 turnip-shaped, conical, funnel-shaped, hori- 

 zontal (extending the whole diameter of tube), 

 sack-shaped. Cloudiness and presence of 

 sediment in liquefied area, and color and shape 

 of sediment, should be described. 

 VII. Potato- culture. 



Describe like agar-slant, adding to it the eventual 



discoloration of the medium. 

 VIII. Litmus milk culture. 



Reaction (acid or alkaline, as indicated by 



color). 

 Coagulation : at ordinary temperature or upon 



heating. 



Whey: if present, clear or turbid. 

 Liquefaction of coagulum (proteolysis, pep- 



tonization). 

 Gas-formation. 



Decolorization of litmus (complete or incom- 

 plete). 



