GENUS BACTERIUM 277 



needle puncture. It is distinctly granular in appearance. 

 Growth does not spread over the surface of the gelatin. Lique- 

 faction does not occur. 



Potato. Frequently growth does not appear on potato. A 

 narrow almost invisible growth along the line of inoculation 

 has been described. 



Serum. The growth on blood serum is like that on agar. 



Bouillon. In alkaline bouillon the growth imparts a faint 

 cloudiness to the liquid. A moderate quantity of rather viscid 

 sediment forms in the tube. The reaction becomes acid. In 

 bouillon containing lactose and saccharose gas is not formed. 

 Dextrose and mannite bouillon become acid and usually gas is 

 formed. In dextrose bouillon about 20% gas is formed in the 

 closed branch of the fermentation tube. The gas formula is 

 C0 2 , 1 part ; H, 3 parts. The action on mannite is practically 

 the same as on dextrose. Some strains of this organism do not 

 produce gas in > any of the sugar media, but acid is formed. 



Milk-. Milk remains unchanged in appearance but after 

 48 hours it becomes slightly more acid although coagulation 

 of the casein does not take place. 



Life conditions and properties. Bacterium pullorum is 

 an aerobe and facultative anaerobe. It develops slowly at 

 room temperature but it grows well at a temperature from 

 36 to 38 C. Neither indol or nitrite is produced. A specific 

 toxin has not been detected. 



Resistance. It is very susceptible to disinfectants. A 

 1-1000 solution of mercuric chloride, a 1% solution of car- 

 bolic acid and 1% creolin emulsion destroy it in five minutes. 

 It resists a temperature of 60 C. for 30 minutes. 



Pathogenesis. Bacterium pullorum is pathogenic for 

 young chicks if inoculated orally within the first forty-eight 

 hours after hatching. It is also pathogenic to chicks three 

 days of age if injected subcutaneously. It causes death in 

 from four days to three weeks and can be recovered from all 

 organs. It is not pathogenic for adult fowls. Two cubic cen- 

 timeters injected directly into the wing vein of adults produced 

 marked depression which lasted for several days but no other 



