532 



PATHOGENIC AEROBIC BACILLI 



be no growth, or it may be scanty and of a white color. In milk, at 

 37 C., an acid reaction and coagulation of the casein are produced at 

 the end of eight or ten days. In the absence of oxygen this bacillus 

 is able to grow in solutions containing grape sugar (Escherich). In 

 bouillon it grows rapidly, producing a milky opacity of the culture 

 liquid. The thermal death-point of Emmerich's bacillus, and of the 

 colon bacillus from faeces, was found by Weisser to be 60 C., the 

 time of exposure being ten minutes. The writer has obtained corre- 

 sponding results. Weisser found that when the bacilli from a bouil- 

 lon culture were dried upon thin glass covers they failed to grow 



Fio. 145. FIG. 146. 



Fia. 145. Bacillus coli communis in nutrient gelatin containing twenty per cent of gelatin, end 

 of two weeks, showing moss-like tufts along the line of growth. (Sternberg.) 



FIG. 146. A portion of the growth shown in Fig 147, at a, magnified about six diameters. 

 From a photograph. (Sternberg.) 



after twenty-four hours. These results give confirmation to the 

 view that the bacillus under consideration does not form spores. 

 This view receives further support from the experiments of Wal- 

 liczek (1894), who found that when dried upon pieces of sterile filter 

 paper the bacillus failed to grow at the end of eighteen hours. 



Pathogenesis. Comparatively small amounts of a pure culture 

 of the colon bacillus injected into the circulation of a guinea-pig 

 usually cause the death of the animal in from one to three days, and 

 the bacillus is found in considerable numbers in its blood. But when 



