CULTIVATION OF THE BACILLUS 



357 



FIG. 118. Cultures of the 

 diphtheria bacillus on an 

 agar plate ; twenty - six 

 hours' growth. 



(a) Two successive strokes ; (b) 

 isolated colonies from the same 

 plate. 



suppuration in the glands, and also various hsemorrhagic con- 

 ditions, have been found to be as- 

 sociated with their presence ; in fact, 

 in some cases the diphtheritic lesion 

 enables them to get a foothold in 

 the tissues, where they exert their 

 usual action and may lead to exten- 

 sive suppurative change, to septic 

 poisoning or to septicaemia. In cases 

 where a gangrenous process is super- 

 added, a great variety of organisms 

 may be present, some of them being 

 anaerobic. Against such complica- 

 tions produced by other organisms 

 anti-diphtheritic serum produce no 

 favourable effect. 



Cultivation. The diphtheria 

 bacillus grows best in cultures at the 

 temperature of the body; growth 

 still takes place at 22 C., but ceases 

 about 20 C. The best media are the 

 following : Lomer's original medium 



(p. 40), solidified blood serum, alkaline blood serum (Lorrain 



Smith), blood agar, and 

 the ordinary agar media. 

 If inoculations be made 

 on the surface of blood 

 serum with a piece of 

 ** diphtheria membranes, 

 ^^iT" 3 ^^ ' Vi c l n i es f tne bacillus 



*V^ JS^ may appear in twelve 



. hours and are well formed 



^. ^v ^ < \ within twenty-four hours 



^&P*J$P often before any other 



^J^AJMr* growths are visible. The 



colonies are small circular 

 discs of opaque whitish 

 colour, their centre being 

 thicker and of darker 



Fie, 119.-Diphtheria bacilli from a twenty- ^ appearance when 

 four hours' culture on agar. Vlewed % transmitted 



Stained with methylene-blue. x 1000. light than the periphery. 



On the second or third 

 day they may reach 3 mm. in size, but when numerous they 



