348 DIPHTHERIA. 



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 produced. This action on the vessels is also ex- 

 emplified 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 degeneration. 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. But probably the most remarkable action is that 

 on the peripheral nerves, which is shown first by the dis- 

 integration of the medullary sheaths as already described, 

 and which is the essential change in most cases of post- 

 diphtheritic paralyses. 



Methods of Diagnosis. The bacteriological diagnosis 

 of diphtheria depends on the discovery of the bacillus. 

 As the bacillus occurs in largest numbers in the mem- 

 brane, 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 obtained, a scraping of the 

 surface with a platinum loop may be sufficient. Where 



