24 INHIBITORY ACTION OF PARATYPHOID BACILLI 



a reduced virulence, acted like a true paratyphoid in inhibiting gas 

 production. 



The rather sharp distinction which this reaction makes between 

 true hog-cholera bacilli and other paratyphoid strains made it seem 

 desirable to test the several members of the dysentery group on 

 hand. All strains tested, including those marked Shiga, Flexner, 

 Hiss Y, Flexner-Harris, and Strong, acted hke the hog-cholera group 

 in that the second or Bacillus coll fermentation was not inhibited as 

 to gas production. Similarly the group of paratyphoid-like bacilli 

 attacking poultry (fowl typhoid and white diarrhea) did not inhibit 

 gas production by Bacillus coli. 



So far, to avoid confusion, the second fermentation has been 

 restricted to two colon strains isolated from a calf. The strain of 

 Bacillus coli used most constantly in the various experiments was iso- 

 lated in December, 1918, from the liver of a calf (No. 302) affected 

 with pneumonia and septic complications. It possesses motility to 

 a certain degree, ferments dextrose and lactose with the accumulation 

 of from 50 to 60 per cent gas in the closed arm of the fermentation 

 tube, and produces a titratable acidity of 4 to 6 per cent of a normal 

 solution. The gas formula H/CO2 is of the usual type, the explosive 

 portion being 2 to 2\ times the CO2 in volume. Saccharose is fer- 

 mented more slowly and about 25 per cent gas accumulates. The 

 second strain (No. 435) was isolated from the spleen of a very young 

 calf affected with digestive derangements, called scours. It was in 

 all cultural characters like the preceding. 



Wherever gas production is referred to in the following pages, the 

 accumulation of gas in the fermentation tube is meant. The acid 

 produced is quoted in per cent of titratable acid in terms of a normal 

 solution. 



It is to be predicted that all races of Bacillus coli will not act alike 

 since there are so many minor distinguishing morphological, cultural, 

 fermentative, and serological features observed among them. Some 

 preliminary tests with other colon bacilli have been made but the 

 data are incomplete. 



