428 A MANUAL OF BACTERIOLOGY 



occasionally in perforative peritonitis and in various 

 septicaemic and pysemic conditions, in the puerperal state, 1 

 complicated stricture, etc. 



The B. Welchii is widely distributed, and has been 

 cultivated from the soil, dust, and contents of the intestine. 

 It has either been described under a variety of names, or 

 a group of closely related bacilli may exist. Gas-bubbles 

 found in the blood and internal organs (" foamy organs ") 

 at an autopsy seem generally to be due to this organism, 

 but may occasionally perhaps be caused by other putre- 

 factive bacteria. 



Morphology. The B. Welchii is a non-motile, sporing, 

 anthrax-like bacillus, variable in size, being 3 to 6 /x in 

 length (Plate XVII. b). It occurs singly, in short chains, 

 or in clumps, and occasionally in long threads. It stains 

 well with the ordinary anilin dyes and also by Gram's 

 method. A capsule is often present, but spores are only 

 formed in blood- serum cultures. 



Cultural characters. The B. Welchii grows well on all 

 the ordinary culture media, slowly at 20 C., rapidly at 

 blood-heat, but is strictly anaerobic. It forms greyish- 

 white colonies on agar, and gelatin is liquefied. In glucose- 

 broth it produces at first a diffuse cloudiness, but later 

 the fluid becomes clear and a whitish viscid sediment 

 settles. Milk is coagulated, the casein forming a thick, 

 stringy, honeycombed mass on the surface of a clear watery 

 whey. On potato the growth is almost invisible. There 

 is abundant formation of gas in culture media, the gas 

 both in dextrose media and in milk, according to Theobald 

 Smith, consisting of hydrogen and carbon dioxide in the 

 ratio 2 : 1 or 3 : 2. 



Pathogenicity. The B. Welchii is pathogenic for guinea- 

 pigs and mice, but slightly so for rabbits. The whey of a 

 milk culture in quantities of 0-5-2 c.c. per 100 grm. of 

 1 See Little, Bull. Johns Hopkins Hosp., vol. xvi, 1905, p. 136. 



