BACILLUS COLI COMMUNIS 



291 



chains. It does not form spores, but sometimes has a capsule; it is 

 rather sluggishly motile, and possesses flagella, generally four to eight, 

 sometimes as few as two, but, according to Loeffler, often as many as 

 ten to twenty. The flagella are generally shorter and thinner than 

 those of the hog cholera bacillus. The bacillus stains with the ordinary 

 watery anilin stains, best with fuchsin; it sometimes shows deeper 

 stained polar granules and unstained portions in the centre. It is 

 Gram negative, like all the other bacilli of the hog-cholera-typhoid- 

 colon group. 



FIG. 145 



FIG. 146 



Bacillus coli communis. X 1000. 

 (Author's preparation.) 



Shiga's dysentery bacillus. X 1000. 

 (Author's preparation.) 



Cultural Properties. It grows best aerobically, but also anaerobically 

 at temperatures from 10 to 37 C., and particularly well at blood 

 temperature. On gelatin plates the colonies appear after eighteen to 

 twenty-four hours. They are grayish white, opaque, and moist; in 

 the depth of the medium they are finely granular and yellowish ; later 

 they become larger, more coarsely granular, and darker. They are 

 round, oval, or whet-stone like. JThe gelatin is not liquefied. In 

 stick cultures the development is * nail-like, and the surface growth 

 becomes relatively abundant, covering the whole surface. On agar 

 the organism forms a grayish-white, rather moist growth. It clouds 

 nutrient bouillon rapidly, and sometimes forms a pellicle. On potatoes 

 an abundant development rapidly occurs; it is yellowish and moist, 

 and markedly elevated. The growth on coagulated blood serum is 

 much like that on agar. Milk is coagulated in consequence of the 

 formation of lactic, acetic, formic, and succinic acids. The colon 

 bacillus ferments glucose, lactose, maltose, saccharose as well as 

 other carbohydrates, and in their presence forms carbon dioxide and 

 hydrogen, generally in the proportion of one to two. Some varieties 

 of the colon bacillus vary considerably as to the amount and proportion 



