PATHOGENIC BACTERIA. 



341 



Bacteriological Diagnosis oj Diphtheria. — In many large 

 cities the bacteriological diagnosis of diphtheria is undertaken 

 by boards of health. The methods used differ somewhat in 

 detail, but are similar in the 

 main, and are based upon the 

 procedure devised by Biggs and 

 Pack for the Board of Health of 

 New York City. Two tubes are 

 furnished in a box. The tubes 

 are like ordinary test-tubes, 

 about three inches in length, 

 rather heavy and without a 

 flange. Both are plugged with 

 cotton. One contains slanted 

 and sterilized LofHer's blood- 

 serum mixture (Fig. 88); the 

 other contains a steel rod, 

 around the lower end of which a 

 pledget of absorbent cotton has 

 been wound. These tubes con- 

 taining the swabs are sterihzed, 

 and it would seem that an effi- 

 cacious method would be to 

 sterilize them first in the auto- 

 clave and subsequently in the 

 dry sterilizer. The swab is wiped 

 over the suspected region in the 

 thoat, taking care that it touches 

 nothing else, and is then rubbed 

 over the surface of the blood- 

 serum mixture. The swab is re- 

 turned to its test-tube and the cotton plugs are returned to their 

 respective tubes. The plugs, of course, are held in the fingers 

 during the operation, and care must be taken that the portion 



Fig. '89. — Bacillus of diphtheria, 

 culture on glycerinagar. 



