CULTIVATION OF THE BACILLUS 



357" 



FIG. 118. Cultures of the 

 diphtheria bacillus on an 

 agar plate ; twenty - six 

 hours' growth. 



(a) Two successive strokes ; (6) 

 isolated colonies from 

 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 : Loffler's original medium 



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



Smith), blood agar, and 



^^iJHlJ^^fe^ th e ordinary agar media. 



If inoculations be made 

 on the surface of blood 

 serum with a piece of 

 diphtheria membranes, 

 colonies of the bacillus 

 *^\ 5^ may appear in twelve 



\ 5 hours and are well formed 



<* .^ *** < I within twenty-four hours 



IgjNiq^j^ often before any other 



^J^jSK growths are visible^ The 



T\ Jv?A colonies are small circular 



discs of opaque whitish 

 colour, their centre being 

 thicker and of darker 

 greyish appearance when 

 viewed by transmitted 

 light than the periphery. 

 On the second or third 

 mm. in size, but when numerous they 



FIG. 119. Diphtheria bacilli from a twenty- 

 four hours' culture on agar. 

 Stained with methylene-blue. x 1000. 



day they may reach 3 



