BACILLUS WELCHII 429 



body-weight produces death in a guinea-pig within forty- 

 eight hours. Post mortem, if injected subcutaneously, 

 the hair strips readily from the skin, which may be green 

 and gangrenous ; the subcutaneous tissue may also be 

 green and gangrenous, or more or less digested, so that the 

 skin hangs loose, and the sac formed contains gas and 

 exudation, sometimes scanty, sometimes abundant, thin 

 and sanguinolent, and containing numbers of bacilli. 

 If the post-mortem be delayed, or if the heart-blood be 

 taken up into tubes, and these are sealed and incubated 

 for some hours, many of the bacilli will spore. Pigeons, 

 by intra- muscular inoculation, are also susceptible. Injected 

 intravenously into a rabbit, the animal killed immediately 

 and the carcase incubated at 37 C. for twenty-four hours 

 and examined, there is an abundant formation of gas, 

 particularly in the liver, which is riddled with gas- 

 bubbles. This is a very characteristic test ( Welch- Nuttall 

 test). 



The B. Chauvcei also produces this " foaming " condition 

 of organs when similarly treated, but spores freely, whereas 

 the B. Welchii does not spore under such conditions. 

 Monkeys fed with considerable numbers of B. Welchii are 

 unaffected. In the human intestine the organism is 

 almost absent or scanty in nurslings and children, but 

 becomes more and more abundant as age advances. It is 

 probable that it is capable of producing necrotic changes 

 in the intestinal mucous membrane. Different strains 

 seem to vary much in virulence. 



Products and toxins. The gas production has already 

 been mentioned. Butyric and allied acids are freely 

 formed, but lactic acid is scanty. Indole may or may not 

 be produced. Hsemolytic substances can be readily 

 detected in blood-bouillon cultures, and the organism is 

 abundant in the intestine in some cases of primary anaemia 

 and possibly may have some relation to the condition. 



