368 DIPHTHERIA 



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 dis- 

 integration 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. 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 

 obtained, a scraping of the surface with a platinum loop may be 

 sufficient. Where the membrane is confined to the trachea the 

 bacilli are often present in the secretions of the pharynx, and 

 may be obtained from that situation by swabbing it with cotton- 

 wool (non-antiseptic), the swab being put into a sterile tube or 

 bottle for transport. A convenient method is to twist a piece of 

 cotton-wool round the roughened end of a piece of very stout 

 iron wire, six inches long, and pass the other end of the latter 

 through a cotton plug inserted in the mouth of a test-tube 

 (compare Fig. 48, the wire taking the place of the pipette), and 

 sterilise. In use the wire and plug are extracted in one piece, 

 and after swabbing are replaced in the tube for transit. A 

 scraping may be made off the swab for microscopic examination, 

 and the swab may be smeared over the surface of a serum tube 

 to obtain a culture. This method of taking and treating swabs 

 is that usually employed in routine public health work. The 

 results obtained ordinarily suffice for the diagnosis of cases 

 suspected to be diphtheritic in nature. 



The means for identifying the bacillus are (a) By micro- 

 scopical examination. For microscopical examination it is 

 sufficient to tease out a piece of the membrane with forceps and 

 rub it on a cover-glass ; if it be somewhat dry a small drop of 



