DISTRIBUTION OF THE BACILLUS 413 



superficial, that is, usually, the oldest part of the false membrane 

 (Fig. 116). There they may be in a practically pure condition, 

 though streptococci and occasionally some other organisms may 

 be present along with them. They may occur also in deeper 

 parts, but are rarely found in the fibrin around the blood vessels. 

 On the surface of the membrane they may be also seen lying in 

 large numbers, but are there accompanied by numerous other 

 organisms. Occasionally a few bacilli have been detected in the 

 lymphatic glands. As Loftier first described, they may be 

 found after death in pneumonic patches in the lung, these 

 being due to a secondary extension by the air passages. They 

 have also been occasionally found in the spleen, liver, and 

 other organs after death. This occurrence is probably to 

 be explained by an entrance into the blood stream shortly 

 before death, similar to what occurs in the case of other 

 organisms, e.g., the bacillus coli communis. The diphtheria 

 bacillus may also infect other mucous membranes. It is found 

 in true diphtheria of the conjunctiva, and may also occur in 

 similar affections of the vulva and vagina ; some of these cases 

 have been treated successfully with diphtheria antitoxin. 



Association with other Organisms. The diphtheria organism is 

 sometimes present alone in the membrane, but more frequently 

 is associated with some of the pyogenic organisms, the strepto- 

 coccus pyogenes being the commonest. The staphylococci, 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 also 

 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, though 

 on experimental grounds the latter is the more probable. We 

 know, however, that some of the complications of diphtheria 

 may be due to the action of pyogenic organisms. The extensive 

 swelling of the tissues of the neck, sometimes attended by 

 suppuration in the glands, and also various haemorrhagic con- 

 ditions, 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 suppurative change, to septic poisoning or 



