412 DIPHTHERIA 



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 toxins, a necrotic action may result when 

 these are injected subcutaneously. The toxins also act upon 

 the blood vessels, and hence oedema and tendency to hemorrhage 

 are produced ; this action on the vessels is also exemplified by 

 the general congestion of organs. The hyaline change in the 

 walls of arterioles and capillaries so often met with in diphtheria 

 is another example of the action of the toxin. The toxins have 

 also a pernicious action on highly developed cells and on nerve 



fibres. Thus in the kidney 

 g. ^ cloudy swelling occurs, 



\ "**^* i W which may be followed 



by actual necrosis of the 

 *tjj secreting cells, and along 



with these changes albu- 

 minuria is present. The 

 action is also well seen in 

 the case of the muscle 

 fibres of the heart, which 







V>*% m &y undergo a sort of 



hyaline change, followed 

 by granular disintegra- 

 tion or by an actual 



- " ; fatty degeneration. These 



FIG. 119. Xerosis bacillus from a young changes are of great 

 agar culture. xlOOO. 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 in 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 to 

 what extent these nerve lesions are of primary nature or 

 secondary to changes in the nerve cells. 



Methods of Diagnosis. The bacteriological diagnosis of 

 diphtheria depends on the discovery of the bacillus. As the 

 bacillus occurs in largest numbers in the membrane, a portion of 

 this should be obtained whenever it is possible, and transferred 

 to a sterile test-tube. (The tube can be readily sterilised by 

 boiling some water in it.) If, however, membrane cannot be 



