234 HrLLETiN 158. 



A Brief Description ok the Gas-Producing Bacillus. 



Source. — Tainted "gassy" cheese curd taken from the vat and 

 from samples of test curds made from the milk of individual 

 cows in the dairy furnishin"^ the milk. 



Morphology. — An actively motile bacillus. In twenty-four 

 hour bouillon cultures the individual organisms are found to vary 

 in length from 2 to 4/x. They have a uniform breadth of 1.2//. 

 They are single with rounded ends- When stained with c^rbol- 

 fuchsin or with carbol-methylene-blue they exhibit a marked 

 polar arrangement of the cellular protoplasm. They stain 

 feebly but uniformly with alkaline methylene-blue. Crystal 

 violet stains the whole of the organism uniformh' and deeph'. 

 It does not retain the stain when treated by the gram method. 

 Flagella are readily demonstrated by Loeffler's method. Spore 

 formation has not been observed. It does not appear to have a 

 capsule. 



Biologic Characters. — This bacillus grows readily on all of the 

 ordinary culture media. Its temperature limitations are from 8° 

 to 40° C. It grows best between 35° and 38° C, and at a low 

 temperature its development is exceedingly slow and feeble. It 

 is aerobic and facultative anaerobic. 



Agar. — Surface colonies on agar plate cultures grown at 37.5° 

 C. are circular, flat, with regular, sharply defined borders. They 

 vary according to the number present, from 2 to 4 mm, in 

 diameter. They are not viscid, neutral gra}^ in color, with 

 moist glistening surfaces. B}- transmitted light the color 

 appears to be darker. The plate cultures emit a penetrating 

 odor resembling slightly that coming from cultures of swine- 

 plague bacteria. The deep colonies are grayish, lenticular shaped 

 masses 0.5 to i mm. in length. In slant cultures the growth is 

 of a neutral gray color usually spreading over the entire surface 

 of the medium. The condensation water is clouded with an 

 accumulating grayish sediment. 



Gelatin. — Colonies on the surface of gelatin plates are thin, 

 spreading, 3 to 7 mm. in diameter, wrinkled, with irregular but 

 sharply defined borders. With transmitted light the centers 

 have an opalescent appearance, these are surrounded with a 



