SUMMAKV OF PATHOGENIC ACTION. 373 



according to Eyre, does not produce an acid reaction in neutral 

 bouillon ; in this way it can be distinguished from the diphtheria 

 bacillus. 



Action of the Diphtheria Bacillus Summary. From 



a study of the morbid changes in diphtheria and of the 

 results produced experimentally by the bacillus and its 

 toxines, the following summary may be given of its action 

 in the body. Locally, the bacillus produces inflammatory 

 change with fibrinous exudation, but at the same time 

 cellular necrosis is also an outstanding feature. Though 

 false membranes have not been produced by the toxines, 

 a necrotic action may result when these are injected sub- 

 cutaneously. The toxines also act upon the blood vessels, 

 and hence oedema and tendency to haemorrhage are pro- 

 duced. This action on the vessels is also exemplified by 

 the general congestion of organs, and sometimes by the 

 occurrence of haemorrhages as in the suprarenal capsules. 

 The hyaline change in the walls of arterioles and capillaries 

 so often met with in diphtheria, is another example of the 

 action of the toxine. The toxines have also a pernicious 

 action on highly -developed cells and on nerve fibres. 

 Thus in the kidney, cloudy swelling occurs, which may be 

 followed by actual necrosis of the secreting cells, and along 

 with these changes albuminuria is present. The action 

 is also well seen in the case of the muscle fibres of the 

 heart, which may undergo a sort of hyaline change followed 

 by granular disintegration or by an actual fatty degenera- 

 tion. These changes are of great importance in relation 

 to heart failure in the disease. Changes of a somewhat 

 similar nature have been recently observed in the nerve 

 cells of the central nervous system, those lying near the 

 capillaries, it is said, being affected first. There is also 

 the striking change on the peripheral nerves, which is shown 

 first by the disintegration of the medullary sheaths as 

 already described. It is, however, still a matter of dispute 

 whether these nerve lesions are of primary nature or are 

 secondary to changes in the nerve cells. 



Methods of Diagnosis. The bacteriological diagnosis 



