BACILLUS HISTOLYTICUS 455 



thick line, from which there are short and stout lateral offshoots, 

 attended by abundant gas formation, while individual colonies are 

 small balls with woolly margin. Superficial colonies have a granular 

 centre and present an arborescent appearance at the edge. The organism 

 rapidly liquefies gelatine and coagulated serum, and also pieces of coagu- 

 lated white of egg. In cooked meat medium there is evolution of gas and 

 rapid digestion ; the meat assumes a dirty, purplish tint, and ultimately 

 becomes blackened. In milk there is a precipitation of casein without 

 actual coagulation, and then digestion rapidly follows. The organism 

 ferments glucose, Isevulose, and maltose, but none of the other sugars 

 ordinarily used. The organism is thus seen to have marked proteolytic 

 properties, and it has been shown to form amino-acids, and as final pro- 

 ducts ammonia, sulphuretted hydrogen, and various volatile substances. 

 It forms large quantities of 

 butyric acid even in sugar- 

 free media (Wolf and 

 . Harris). 



The b. sporogenes has *»■ 



little or no pathogenic pro- J ■ 



perties when injected in ■' 

 animals, a comparatively p / 



large amount of pure cul- / a7" v "V — 



ture producing only a local f* » 



swelling which passes off; j 



and observations on gunshot _ £ 



wounds supply no evidence \ ' **~ 



that it invades the healthy \ ^ 



tissues. It may be regarded s^B . *■ . / 



chiefly as a proteolytic I ■ ' 



saprophyte which grows on I 



dead and dying tissues , 



and brings about digestive ' ^_ ^4 ~- - ' 



softening and putrefactive — - — 



kvXs'the^tislues already **>• 132 - B - 3 P or °S- es > *™ cu]ture ' show " 

 mvaaes tne tissues already ing sub-terminal spores. 



damaged by other organ- stained with carbol-thionin blue. xlOOO. 



isms, e.g., the b. welchu. 



There is also experimental 



evidence that its presence aids the pathogenic effects of other organisms. 



The b. sporogenes is closely allied to another anaerobe described under 



the name b. putrificus. 



Bacillus histolyticus. — This is another proteolytic and putrefactive 



anaerobe separated by Weinberg from cases of gas gangrene. It is 



2-6 11 in length and rather thinner than the b. welchii ; it is often 



arranged in pairs. It is Gram-positive and forms large oval subterminal 



spores. The surface growth is in the form of a very thin film, with 



offshoots at the margin. Its action on milk and coagulated serum is 



similar to that of the 1>. sporogenes, but is even more rapid. In cooked 



meat medium also it produces very rapid digestion, with foul odour, and 



one feature described by Henry is the separation of white balls of 



acicular crystals which are probably tyrosin — an appearance which is 



probably characteristic of this organism. The cultures have a foul 



odour. A striking evidence of the proteolytic action of this organism 



is seen when it is injected subcutaneously in a guinea-pig. A rapid 



