GENUS BACILLUS 335 



attended with some difficulty. It is an obligatory anaerobe. 

 It grows at a temperature between 38 and 40 C. The op- 

 timum temperature is about 35 C. It does not grow readily 

 on ordinary media although we have obtained fairly good cul- 

 tures on agar. Agar-gelatin,* serum-agar and serum-agar- 

 gelatin have been recommended. Several other media have 

 been suggested. 



Agar. Liborius cultures in from 36 to 48 hours show 

 greyish white colonies in the depth of the medium. These 

 have later a dense whitish or yellowish center with a more or 

 less opaque cloudiness about them. Mohler refers to gas 

 bubbles appearing in the medium. On serum agar the growth 

 is similar to that on agar. 



Gelatin. The growth is feeble on this medium. The gela- 

 tin is not liquefied. 



Bouillon. This medium becomes turbid. The bacteria 

 settle later in the form of whitish viscid flakes and the fluid 

 becomes clear. Ernst has described the odor as being between 

 that of cheese and glue. Mohler observed gas bubbles. 



Milk. Milk is said not to be coagulated nor to become 

 more acid. 



Liquid serum. Mohler states that liquid serum is coagu- 

 lated. 



Life conditions and properties. B. nccrophorus requires 

 the absence of atmospheric oxygen. It produces indol. Its 

 toxic production is not clearly determined. It has been 

 thought by some that it elaborated a specific and important 

 toxin because of the nature of the lesions it produces. The 

 enormous number of bacilli present in the necrotic tissue sug- 

 gests possibly that the excessive multiplication of the bacilli 

 may be largely responsible for the result. 



Resistance. B. necrophorus is destroyed after an exposure 

 for 2 minutes in. a 3^ solution of carbolic acid. Corrosive sub- 

 limate and formalin destroy it in weak solutions. 



Pathogenesis. This organism affects nearly all species 

 of domesticated animals and it is reported as being found in 



* Serum and agar equal parts. 



