522 THE ANTHRAX BACILLUS 



In the living tissues the bacilli never form spores, reproduction taking 

 place solely by. fission. 



Staining methods. The bacillus is readily stained by all the basic aniline 

 dyes. It is gram-positive. After staining it will be noticed that the ends 

 are never rounded but always square cut. Under very high magnification 

 the ends show an outline which is [ragged or] sinuous rather than straight, 

 as though the bacillus had been roughly broken. This appearance is charac- 

 teristic of the organism. On account of its large size an oil-immersion lens 

 is not generally necessary for the examination of microscopical preparations, 

 a high -power dry objective being of sufficient magnifying power. 



Staining of films and sections. Gram's method will be used for choice in 

 searching for and identifying the organism in blood films, smears and sections. 

 The mesentery and films and smears of the internal organs should be stained 

 by the double method (eosin and violet), sections by the double or triple 

 method (Orth's picro-carmine and violet). The technique is described 

 fully at p. 219. 



Capsules. The bacillus of anthrax in the blood and in smears from the 

 spleen frequently shows a very distinct capsule (Serafini). This capsule is 



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A 



FlG. 251. Bacillus anthracis. Blood film from an ox dead of anthrax. 

 Jenner's stain. (Oc. 2, obj. ^th, Zeiss.) 



visible in preparations stained by carbol-thionin or carbol-blue and may 

 also be demonstrated by the ordinary methods for staining capsules (p. 148). 

 [In examining blood from an animal suspected to have died from anthrax 

 the film is best stained either with Jenner's stain or with an alkaline solution 

 of methylene blue. With Jenner's stain the organism shows a well marked 

 capsule. The bacillus itself stains blue while the capsule assumes a delicate 

 pink tint. This method has been found of the utmost value in practice and 

 enables a distinction to be drawn at sight between the anthrax bacillus and 

 the bacillus of malignant oedema, an organism by no means infrequently 

 found in blood-films made from dead animals.] 



(ii) Filamentous form. 



In cultures the anthrax bacillus usually occurs in long filaments which are 

 best studied in a broth culture in which they are longer than on solid media. 



