90 LABORATORY GUIDE IN BACTERIOLOGY 



Determine the percentage of gas formed and the gas 

 formula. Compare the results with those of the other 

 intestinal groups. How does the gas formula differ 

 from those previously examined ? 



NOTE. In order to obtain a clear picture of the chief differ- 

 ential characteristics of the four intestinal groups, it is recom- 

 mended to tabulate the results in parallel columns, as outlined 

 below. Express positive results by the sign + ; negative, by . 

 Complete agglutination is expressed by + + ; slight, by -f . 



