PATHOGENIC EFFECTS 



445 



effects in milk are practically the same as those described by 

 Klein in the case of his bacillus enteritidis sporogenes, and the 

 two organisms concerned in them are probably the same, though 

 it is now generally held that Klein's cultures were impure, the 

 b. sporogenes (vide infra) or some allied putrefactive organism also 

 being present. In cooked meat medium the b. welchii produces a 

 pink colour with considerable amount of gas ; there is a sour smell, 

 but no putrid odour or blackening of the medium. The organism 

 may be said generally to be an active fermenter of sugars and 

 some other substances, though strains differ somewhat in this 

 respect. It produces acid 

 and gas from glucose, 

 maltose, lactose, saccha- 

 rose, and starch, and also 

 from glycerine ; inulin 

 is sometimes fermented, 

 sometimes not. Fer- 

 mentation of these sub- 

 stances takes place with 

 great rapidity, but the 

 acid formed has a 

 markedly deterrent 

 action on the growth, 

 and soon leads to its 

 cessation. The b. welchii 

 has thus very active 

 saccharolytic action, 

 whereas its digestive 

 effect on proteins is 

 almost nil, and these 

 properties will be found 

 to have an important bearing on its pathogenic effects. 



Pathogenic Effects. — In addition to invading the blood stream 

 about the time of death, and giving rise to gas cavities in the 

 organs, the bacillus welchii has been found in various emphy- 

 sematous and gangrenous conditions in civil life, the infection 

 usually starting in connection with the alimentary canal. It is 

 also, as has been indicated, by far the most important cause of 

 gas gangrene from war wounds. In this affection it is now 

 recognised that the starting-point is usually some laceration of 

 muscle, which has become contaminated with soil containing the 

 bacillus. The spread of the disease is often remarkable, as cases 

 have been recorded in which extensive emphysematous swelling 

 with gangrene of a limb has occurred with a fatal result, well 



Fig. 128. — Bacillus welchii, showing capsules ; 

 film preparation from bone-marrow in a 

 case where gas cavities were present in the 

 organs, x 1000. 



