358 DIPHTHERIA. 



towards the superficial, that is, usually, the oldest part of 

 the false membrane (Fig. 90). There they may be in a 

 practically pure condition, though streptococci and occa- 

 sionally some other organisms 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 

 Loffler first described, they may be found after death in 

 pneumonic patches in the lung, this being a secondary 

 extension by the air passages. They have also been occa- 

 sionally found by various observers 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. With these 

 exceptions, however, it may be stated that the bacillus of 

 diphtheria occurs only locally in the false membrane and 

 in the fluids of the mouth, and does not invade even the 

 subjacent tissues to any extent. 



Association ivith other Organisms. The diphtheria 

 organism is sometimes present alone in the membrane, 

 but more frequently associated with some of the pyogenic 

 organisms, the streptococcus pyogenes being the com- 

 monest. The staphylococci, and occasionally the pneumo- 

 coccus 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 in- 

 flammation 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 



