378 J' RUSSELL ESTY 



in considerable numbers. Two cans of preserved tomatoes 

 packed by the cold pack method showed evidence of gas fermen- 

 tation and when cultures were isolated anaerobically, Clostridium 

 Welchii was found to be the cause of the fermentation. This 

 organism therefore appears to have as broad a distribution as 

 Bacterium coli. 



TABLE 1 

 The number of cultures used in the subsequent study by sources 



IV. MORPHOLOGY 



1. Size and shape of organisms. Clostridium Welchii usually 

 appears in cultures as a straight, plump rod, varying in size 

 from 3 to 6 micra in length and from one to one and a half micra 

 in breadth, according to the nature of the medium. The ends 

 of the rods are slightly rounded or square cut. In old cultures 

 the rods may be slightly curved or may form threads, filaments 

 or long chains. In freshly isolated cultures they occur singly, 

 paired, in clumps and sometimes in short chains of three to six 

 bacilli, with the rods in a straight line or at an angle. Cultures 

 grown for a long time on bloodserum and in liquid media con- 

 taining coagulated egg-white, show long chains, rather slender 

 threads and filaments, varying in length from 5 to 6 micra to 

 threads extending across the microscopic field. Variation is 

 more pronounced in the presence of a fermentable substance. 

 An acid reaction is more favorable to variation than an alkaline 

 reaction. The rods are more slender in gelatin and nutrient 

 broth than in other media. In milk cultures the organisms are 

 comparatively short, presenting a coccoid appearance. Greater 



