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- 

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

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



+m 



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FlG. 2. Showing capsules and formation of zooglcea. 



Streptococcus mesenterioides after Zopf. B. Streptococcus capsulatus after Binaghi. 

 C. Hact.anthracisa.her Babes. D. capsule bacillus, Babes. . a bacillus simulating 

 typhoid, Babes. YV. B. typhosus after Babes and Ldwit. G. ffact. 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 Bad. pneumonia when found 

 in the body fluids shows a much thicker capsule than when 

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



