96 ESSENTIALS OF BACTERIOLOGY 



Growth. Slow; is facultative anaerobic. Grows at 10 C. 



Plate Colonies. First small white points, which soon look like 

 porcelain, glistening. Under microscope the surface colonies 

 resemble leaves spread out. 



Stab-culture. A thick dry crust with cracks in it forms on the 

 surface after a couple of weeks. 



Attenuation. If grown through successive generations, they 

 lose the power to produce fermentation. Several other bacteria 

 will give rise to lactic-acid fermentation; but this especial 

 one is almost constantly found and is very widespread. 



In milk it first produces acidity, then precipitation of casein, 

 and, finally, formation of gases. 



A bacillus described by Grotenfeldt, and called Bacterium 

 acidi lactici, forms alcohol in the milk. It was found in milk 

 in Bavaria. 



Boas-Oppler Bacillus. Also known as the Bacillus genic- 

 ulatus. Owing to the faculty possessed by this organism of 

 growing in the presence of amounts of lactic acid sufficient to 

 check the development of all other lactic-acid formers, it usually 

 predominates in stomach-contents containing large amounts of 

 this substance. The parent type is composed of short rods, 

 but in the presence of considerable amounts of lactic acid these 

 change to a longer form, which occurs singly or in long chains. 

 It is stained brown by Gram's iodin solution. The bacillus 

 affords confirmatory evidence of the. presence of a new growth, 

 though it may occur in benign conditions. 



Bacillus Butyricus (Hiippe). This bacillus causes buty- 

 ric-acid fermentation. 



Origin. Found in milk. 



Form. Short and long thin rods with rounded ends; large 

 oval spores, seldom forming threads. 



Properties. Very motile; liquefies gelatin rapidly; produces 

 gases resembling butyric acid in odor. In milk it coagulates the 

 casein, decomposes it, forming peptones and ammonia, with a 

 bitter taste, and butyric-acid fermentation. An alkaline reaction. 



Growth. Quickly, at 35 to 40 C., with oxygen. Spores 

 very resistant. 



