CHAPTER XL. 



BACTERIA, GENERALLY NOT PATHOGENIC, OFTEN EMPLOYED IN 

 LABORATORY PRACTICE BACILLI OF THE PROTEUS GROUP- 

 BACILLUS ANTHRACOIDES BACILLUS MEGATHERIUM- 

 BACILLUS PRODIGIOSUS BACILLUS VIOLACEUS 

 BACILLUS CYANOGENUS MICROCOCCUS 

 TETRAGENUS MICROCOCCUS AGILIS 

 SARCINA LUTEA. 



Bacilli of the Proteus Group. Members of this group were first 

 isolated from decaying animal material. They are aerobic and 

 facultative anaerobic organisms which in their growth decompose 

 proteid materials and produce a very fetid smell. They are named 

 proteus because they are exceedingly variable in their morphology. 

 While in their most typical shape they are bacilli of medium size, they 

 appear, particularly in older cultures, in short coccoid form and also 

 in curved vibrio-like shape. They stain with ordinary watery anilin 

 solutions, but are generally Gram negative and do not form spores. 

 The most common type of this group is the Bacillus proteus vulgaris 

 of Hauser. This organism varies in length from 1.2 to 4 micra and 

 more and is 0.6 micron wide. It is lively motile and possesses a large 

 number of flagella distributed around the entire body. The growth 

 on 5 per cent, gelatin is very typical. At room temperature round, 

 depressed, whitish colonies are formed which send out wreaths of 

 filamentous projections into the surrounding, not yet liquefied, medium. 

 As the liquefaction goes on the peripheral portions of the growth 

 break away from the principal mass and swarm about in the liquefied 

 medium. This wandering away can be observed under a .medium or 

 low power of the microscope. In firmer gelatin of a higher concentra- 

 tion this swarming of broken-off portions of the colonies does not 

 occur. The growth is best at 24 C., but it is still quite abundant at 

 37 C. The bacillus, when grown under anaerobic conditions, does 

 not liquefy gelatin. Upon agar the bacillus forms a moist, thin, 

 transparent growth. Milk is coagulated. It produces indol and 

 phenol and reduces nitrates to nitrites. Glucose and saccharose are 

 fermented, but not lactose. If injected in small amount subcutaneously 

 into animals no ill effect is produced. Larger doses introduced 

 intravenously or intraperitoneally produce death under symptoms 

 pointing to intoxication. The Bacillus proteus vulgaris does not 

 multiply in healthy tissues, but it can grow in necrotic tissues, and 

 has been found in wounds. It furnishes a soluble toxin which causes 



