4 



BACTERIOLOGY 



small portion of an agar culture with a drop of water is faulty, 

 inasmuch as there is always danger of the water dissolving a 

 portion of the capsule. The better method is to touch the edge 

 of a square cover-glass to a portion of an agar culture ; and 

 then draw this contaminated edge over the surface of a second 

 cover-glass, thus forming a thin film which dries instantly. The 

 cover-glass is then at once immersed in a 4 per cent forma- 

 hne solution to fix the film. The latter can then be stained by 

 Lowit's method, which the author has found preferable to that 



Fig. 2. — Showing capsules and formation of zoogloea. 



Streptococcus mesenterioides after Zopf. B. Streptococcus capsulatus after Binaghi_ 

 C. Bad. anthracis after Babes. D. capsule bacillus, Babes. E. a bacillus simulating^ 

 typhoid, Babes. FF. B. typhosus after Babes and Lowit. G. Bact. Pasteurianum after 

 Hansen. 



of Loffler (see p. 6). The form of the enveloping capsule- 

 varies in different species : in Fig. 2, E, it is rather thick and 

 symmetrical with the central body ; at F, of the same figure, the- 

 capsule shows a number of angular processes to which individual 

 flagella are attached. The thickness of the capsule is governed 

 in certain cases by the chemical properties of the medium in 

 which the organism grows. Thus Bact. pneumonicB when found 

 in the body fluids shows a much thicker capsule than when, 

 grown on ordinary culture media. In certain species, as Strep- 



