CULTIVATION OF BACILLUS 



477 



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enlargement of all the bacilli. Sometimes in the tissues they 

 are seen to be surrounded _____ 



by an unstained capsule, 

 though this appearance is 

 by no means common. 

 They do not form spores. ^T, 

 Gordon, who has found >\^ 

 that they possess 

 which, however, stain with 

 difficulty, states that they 

 are motile. Most ob- 

 servers, however, and with 

 these we agree, have 

 failed to find evidence ui r - t . 



true inotility. They stain * ' ** H^' 



readily with the basic * J^s~~ ' 



aniline stains, but are 



, FIG. 142.- Bacillus of plague from a young 



decolorised by Grams culture on agar. 



i lift hod. Stained with weak carbol-fuchsiii. x 1000. 



Cultivation. From the 



atl'rcted glands, etc., the bacillus can readily be cultivated on 



the ordinary media. It grows best at the temperature of the 



body, though growth 

 occurs as low as 18 C. 

 On agar and on blood 

 serum the colonies are 

 whitish circular discs of 

 somewhat transparent 

 appearance and smooth, 

 shining surface. When 

 examined with a lens, 

 their borders appear 

 slightly wavy. In stroke 

 cultures on agar there 

 forms a continuous line 

 of growth with the 

 same appearance, show- 

 ing partly separated 



FIG. 143 -Bacillus of plague in chains show- colonies at its margins, 

 ing polar staining. From a young culture , I7 , 



in bouillon. When agar cultures are 



Stained with thionin-blue. x 1000. kept at the room tempera- 

 ture, some of the colonies 



may show a more luxuriant growth with more opaque appearance 



than the rest of the growth, the appearance in fact being often 



