GENERAL PRINCIPLES 157 



Broth. Inoculate from agar cultures three broth tubes, 

 one with each of the following bacilli : B. fluorescens 

 liquefaciens, B. subtilis, and B. mycoides. Incubate at 

 20 C. and examine in twenty-four or forty-eight hours. 

 Culture of B. fluorescens liquefaciens, quite turbid, or 

 " universal turbidity " ; of B. subtilis, quite clear but scum 

 is formed ; of B. mycoides, quite clear but deposit is 

 formed. 



Gelatin. Three forms of culture : (i) slant or streak, 

 (2) stab, (3) shake. 



1. Slant or streak for non-liquefying organisms. 

 Inoculate sloped tubes with B. coli communis and Torula 

 alba. Incubate at 20 C. and examine after forty-eight 

 hours. 



B. coli communis, spread over surface ; Torula alba, 

 growth limited to line of inoculation. 



2. Stab culture to observe presence or absence of 

 liquefaction. Inoculate gelatin tubes by stabbing with 

 B. mycoides, B. megatherium, and Vibrio Finkler-Prior. 

 Incubate at 20 C. and examine after twenty-four, forty- 

 eight, and seventy-two hours. 



B. mycoides, horizontal liquefaction ; B. megatherium, 

 funnel of liquefaction medium width ; V. Finkler-Prior, 

 funnel of liquefaction wide. 



3. Shake culture to observe gas formation. Melt 

 gelatin at 40 C. on water-bath and inoculate as in the 

 case of broth. Place in rack, and allow to solidify. 

 Incubate for forty-eight hours. Use B. coli communis and 

 B. subtilis. 



B. coli communis, gelatin full of gas bubbles ; B. subtilis, 

 no gas formed. 



Agar. Inoculate sloped agar tubes with the following 

 germs, incubate at 37 C., and examine after twenty- 

 four hours. 



Results should be as follows : B. subtilis, dry myco- 

 derma ; B. mycoides, fine filaments ; B. megatherium, 

 confluent moist raised growth ; B. proteus, thin transparent 

 growth over whole surface. 



Potato. Inoculate, incubate at 37 C., and examine in 

 twenty-four hours. 



