360 DIPHTHERIA. 



the superficial, that is, usually, the oldest part of the false mem- 

 brane (Fig. 120). There they may be in a practically pure 

 condition, though streptococci and occasionally some other or- 

 ganisms may be present along with them. They may occur 

 also deeper, 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 usually accompanied 

 by numerous other organisms of various kinds. Occasionally 

 a few bacilli have been detected in the lymphatic glands. As 

 Loffier first described, they may be found after death in pneu- 

 monic patches in the lung, this being a secondary extension by 

 the air passages. They have also been occasionally found by 

 various observers in the spleen, liver, and other organs after 

 death. This occurrence is probably to be explained by an en- 

 trance 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 con- 

 junctiva, and may also occur in similar affections of the vulva 

 and vagina : some of these cases have been treated success- 

 fully with diphtheria antitoxin. The pseudo-diphtheria bacillus, 

 however, may also occur in these situations. 



Association with other Organisms. The diphtheria organ- 

 ism is sometimes present alone in the membrane, but more fre- 

 quently is associated with some of the pyogenic organisms, the 

 streptococcus pyogenes being the commonest. The staphylo- 

 cocci, and occasionally the pneumococcus or the bacillus coli, 

 may be present in some cases. Streptococci are often found ly- 

 ing 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 mem- 

 brane was thinner and softer, the appearance in these cases be- 

 ing 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 exten- 



