6i6 LABORATORY HINTS 



Pure cultures can be formed by inoculating a guinea-pig from 

 tubercular sputum. 



(2) The Bacillus pseudo-tuberculosis of Pfeiffer. 



It grows rapid! V and readily forms a creamy growth on agar very 

 different from that of tubercle. On gelatin a whitish growth without 

 liquefaction. It is not acid-fast. Is Gram-negative. Found in milk 

 and sewage. Pathogenic to guinea-pigs and rabbits. 



(3) The Bacillus leprae. 



A long slender straight rod, with somewhat pointed extremities, 

 non-motile, does not form spores. Gram-positive. Acid-fast. 



Stains more rapidly and decolorizes more readily than the tubercle 

 bacillus. Attempts to grow cultures have not been very successful. 



(4) The Smegma Bacillus. 



Shorter and flatter than the tubercle bacillus in cultures. 

 Grows readily, acid-fast. 

 Non-pathogenic in small infections. 



(6) The Bacillus of Timothy Grass. 



Acid-fast. Resembles tubercle bacilli, but is harmless. 

 It grows readilv in any ordinary medium. 



It is found in fodder about cow-sheds, and when in milk may be 

 taken for the tubercle bacillus. 



The chief ones from the spore-forming groups are : — 



(1) The Anthrax Bacillus. 



It is aerobic and facultatively anaerobic. 5 to 6 /a long. 



Non-motile, scjuare ends, occurs in short chains and singly in blood. 



Some segmentation may be seen on staining. It is surrounded by 

 a sheath in which it divides; this process may continue, forming 

 chains. 



In the presence of much oxygen and a temperature of 20° to 38° 

 C., spores are developed, but only after death when the blood dis- 

 charges come into contact with the air. In cultures it liquefies gelatin 

 in two days. 



In a stab, fine branching filaments grow outwards from the needle 

 track called the " inverted fir tree growth." Liquefication begins at 

 the top. 



In both a focculent growth forms at the bottom. 



On agar a thick grey-white sticky growth. 



The bacilli are Gram-positive. 



To stain spores heat them for twenty minutes in warm carbol 

 fuchsin. 



