PATHOGENIC ANAEROBIC BACILLI. 



539 



when oxygen is excluded in an atmosphere of hydrogen. Grows 

 at the room temperature better in the incubating oven at 37 C. 

 The spores are formed most abundantly in cultures kept in the in- 

 cubating oven, but may also be formed at a temperature of 20 C. 

 In the bodies of animals which succumb to an experimental inocula- 

 tion no spores are found immediately 

 after death, but the bacilli multiply rap- 

 idly in the cadaver, and form spores 

 when the temperature is favorable. 



The malignant- oedema bacillus may 

 be cultivated in ordinary nutrient gela- 

 tin, but its development is more abun- 

 dant when one to two per cent of grape 

 sugar has been added to the culture 

 medium. In deep stick cultures in this 

 medium development occurs at first only 

 near the bottom of the line of puncture ; 

 the gelatin is liquefied and has a grayish- 

 white, clouded appearance ; an abundant 

 development of gas occurs, and as this 

 accumulates the growth and liquefaction 

 of the gelatin extend upward. A very 

 characteristic appearance is obtained 

 when the bacilli are mixed in a test 

 tube with gelatin which has been liquefied by heat, and which is then 

 allowed to solidify. Spherical colonies are developed, in the course 

 of two or three days, in the lower portion of the gelatin ; these are 

 filled with liquefied gelatin of a grayish- white color, and when ex- 

 amined with a low power are seen to be permeated with a network 

 of filaments, while the periphery presents a radiate appearance. In 

 nutrient agar growth also occurs at the bottom of a deep punc- 

 ture ; it has an irregular, jagged outline and a granular appearance; 

 the considerable development at the deepest portion and gradual 

 thinning out above give the growth a club shape ; in the incubating 

 oven there is an abundant development of gas, which often splits up 

 the agar medium and forces the upper portion against the cotton 

 stopper. An abundant development of gas also occurs in cultures 

 in blood serum, and the medium is rapidly liquefied ; at a tempera- 

 ture of 37 it is changed in a few days to a yellowish fluid, at the 

 bottom of which some irregular, corroded fragments of the solidified 

 serum may be seen. In agar plates, placed in a close receptacle 

 from which oxygen is excluded, cloudy, dull-white colonies are 

 formed which have irregular outlines and under the microscope 

 are seen to be made up of branching and interlaced filaments radi- 



Fio. 166. Bacillus oedematis ma- 

 ligni, cultures in nutrient gelatin; a, 

 long stick culture; 6, colonies at bot- 

 tom of gelatin tube. (Flugge.) 



