416 J. RUSSELL ESTY 



was not calculated in every case before inoculation but those 

 tested showed acidities (Fuller's scale) ranging from 1.2 to 3.5 

 per cent in terms of N NaOH with phenolphthalein as an indicator. 

 In the case of the twenty-four hour culture where the greatest 

 acidity was produced, mild local infections occurred and in one 

 case death after nine days. In one instance the amount of acid 

 produced by the multiplication of the bacilli in the tissues was 

 determined. Death occurred in twenty hours after the injection 

 of a lethal dose and at autopsy the tissue surrounding the necrotic 

 area was titrated with phenolphthalein as an indicator. It was 

 found that the acidity had reached approximately 12 per cent 

 before the death of the animal, showing again the ability of 

 Clostridium Welchii to produce acid by means of utilizing the 

 carbohydrates in the tissues. In two cases, the virulent broth 

 cultures were neutralized with NaOH which when injected in 

 lethal doses in the subcutaneous tissues of guinea-pigs proved 

 fatal, presenting the same symptoms and effects as the un- 

 neutralized cultures. The same effects were produced if the 

 sedimented bacilli were injected or the supernatant fluid, pro- 

 vided a sufficient dose was given. Although sufficient experi- 

 ments have not been performed for definite conclusions regard- 

 ing the role of acidity, yet the results already at hand point 

 conclusively to the exclusion of this factor in bringing about the 

 fatal effects. If the acidity factor aids in the destruction of the 

 tissues, the effect is secondary in the production of fatal results. 



If.. Discussion of results. Animals are more susceptible, and 

 smaller doses are more liable to kill, when the inoculations are 

 subcutaneous or intramuscular than when other modes of inocu- 

 lation are employed. The difficulty encountered with the intra- 

 venous inoculation for guinea-pigs made it impracticable for 

 routine work. In the one successful attempt, however, it proved 

 very fatal, 0.1 cc. being sufficient to kill a 500-gram guinea-pig. 

 The minimum lethal doses for virulent cultures when injected 

 subcutaneously and intraperitoneally are 0.1 cc. and 0.25 cc. 

 respectively for 600-gram guinea-pigs. The minimum lethal 

 dose was not determined for rabbits. 



