CULTIVATION OF BACILLI. 335 



and occasionally the pneumococcus or the bacillus coli, 

 may be present in some cases. Streptococci are often 

 found lying side by side with the diphtheria bacilli in the 

 membrane, and sometimes found penetrating more deeply 

 into the tissues. In some cases of tracheal diphtheria, we 

 have found streptococci alone, at a lower level in the trachea 

 than the diphtheria bacilli, where the membrane was 

 thinner and softer, the appearance in these cases being as 

 if the streptococci acted as exciters of inflammation and 

 prepared the way for the bacilli. It is still a matter of 

 dispute as to whether the association of the diphtheria 

 bacillus with the pyogenic organisms is a favourable sign or 

 the contrary, nor is it certain what part they play locally in 

 the disease. We know, however, that some of the com- 

 plications of diphtheria may be due to their action. The 

 extensive swelling of the tissues of the neck, sometimes 

 attended by suppuration in the glands, and also various 

 haemorrhagic conditions, have been found to be associated 

 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 extensive sup- 

 purative change, or to septic poisoning. In cases where a 

 gangrenous process is superadded, a great variety of organ- 

 isms may be present, some of them being anaerobic. 



Against such complications anti-diphtheritic serum pro- 

 duces no favourable effect, as its action is specific and only 

 neutralises the toxines of the diphtheria bacillus. In view 

 of this fact, in some cases the anti-streptococcic serum has 

 been used along with it, and it is apparent that in such con- 

 ditions the bacteriological examination of the parts affected 

 may afford valuable indications as to treatment. 



Cultivation. The diphtheria bacillus grows best in 

 cultures at the temperature of the body ; growth still takes 

 place at 22 C, but ceases at 20 C. The best media are 

 the following : Loffler's original medium, 1 solidified blood 



1 3 parts calf's or lamb's blood serum, plus i part of ordinary peptone 

 bouillon made from veal and containing, in addition, i per cent grape 

 sugar. Inspissate as with ordinary serum. 



