BACTERIOLOGICAL TECHNIC 57 



Coagulation: present or absent. 

 Note. — ^I£ acid has formed but no coagulation is evident after 

 six days, heat gently and see whether coagulation then takes 

 place. 



Whey: if present, clear or turbid. 



Liquefaction of coagulum (proteolysis). 



Gas formation. 



Decoloration of litmus. 



Color of cream ring. 



Odor. 



In milk the presence or absence of coagula- 

 tion and proteolysis should be noted. Com- 

 pare your culture with a sterile milk tube. 



IX. Broth culture. 



Cloudiness: degree and uniformity; scum 



(ring- or island-shaped). 

 Precipitate, observed by shaking. Amount, 

 color, formation, diffusibility, viscidity, 

 amount of precipitate. 

 X. Solidified blood serum. 



Describe like agar slant, and note presence or 

 absence of liquefaction, 



XI. Fermentation tubes. 



Gas formation in closed arm, percentage and 

 relation of carbon dioxid to hydrogen ex- 

 pressed in simple figures by the formula 

 H 



CO/ 

 Growth in both arms or in one arm only, 



observed by cloudiness. 

 Reaction: acid or alkaline to litmus. 



