BACILLUS MUCOSUS CAPSULATUS 449 



equally well on moderately alkaline or acid media. It is aerobic and 

 facultatively anaerobic; growth under anaerobic conditions, however, 

 is not luxuriant. 



On agar, growth appears in the form of grayish-white mucus-like 

 colonies, having a characteristically slimy and semi-fluid appearance. 

 Colonies have a tendency to confluence, so that on plates, after three or 

 four days, a large part of the surface appears as if covered with a film of 

 glistening, sticky exudate, which, if fished, comes off in a tenacious, 

 stringy manner. It is often possible to make a tentative diagnosis of 

 the bacillus from the appearance of this growth. 



In broth, there is rapid and abundant growth, with the formation 

 of a pellicle, general clouding, and later the development of a profuse, 

 stringy sediment. 



Stab cultures in gelatin show, at first, a white, thin line of growth 

 along the course of the puncture. .Soon, however, rapid growth at 

 the top results in the formation of a grayish mucoid droplet on the 

 surface, which, enlarging, gives the growth a nail-like appearance. This 

 nail-shape was originally described by Friedlander and regarded as diag- 

 nostic for the bacillus. The gelatin is not fluidified. As the culture grows 

 older the entire surface of the gelatin tube may be covered with growth, 

 flowing out from the edges of the nail-head. The gelatin acquires a darker 

 color and there may be a few gas bubbles below the surface. Micro- 

 scopically, colonies on gelatin plates have a smooth outline and a finely 

 granular or even homogeneous consistency. 



On blood serum, a confluent mucus-like growth appears. 



On potato, abundant growth appears, slightly more brownish in color 

 than that on other media. 



In pepton solutions, there is no indol formation. 



In milk, there is abundant growth and marked capsule develop- 

 ment. Coagulation occurs irregularly. 



In considering the general cultural characteristics of the Fried- 

 lander bacillus, it must not be forgotten that we are dealing with a 

 rather heterogeneous group, the individuals of which are subject to 

 many minor variations. Capsule development, lack of motility, in- 

 ability to fluidify gelatin, failure to form indol, and absence of spores, are 

 characteristics common to all. In size, general appearance, gas forma- 

 tion, and pathogenicity, individual strains may vary much, one from 

 the other. Strong 1 has studied various races as to gas formation and 



1 Strong, Cent. f. Bakt., xxv, 1899. 



