94 APPLIED BACTERIOLOGY FOR NURSES 



tion of a peculiar dirty gray membrane on the surface of 

 the part. This membrane consists of fibrin, pus cells, 

 and granular debris, and contains numerous diphtheria 

 bacilli. Somewhat similar membranes, however, are 

 produced by other bacteria, especially by streptococci, 

 and, while an experienced clinician can often tell by 

 the appearance of the membrane whether the infection is 

 due to the diphtheria bacillus or not, most physicians 

 prefer to have the diagnosis established by bacteriologic 

 examination. This should be done by spreading some 

 of the membrane on a slide, fixing, and staining with 

 Loffler's alkaline methylene-blue, and then examining 

 under the microscope. In addition, where the facilities 

 are at hand, by means of a sterile swab rubbed first 

 over the membrane, and then over the surfac'e of a tube 

 of sterile Loffler's serum, a culture is made, incubated for 

 from twelve to eighteen hours, and the growth ex- 

 amined under the microscope. In cases of true diph- 

 theria such a culture will usually show enormous num- 

 bers of diphtheria bacilli. Both methods should be 

 employed in order to insure a correct diagnosis, for cer- 

 tain germs, for example, those of Vincent's angina, will 

 not grow on the culture-medium. 



Knowing the location of the diphtheria bacilli, it is 

 not difficult to devise measures to prevent the infection 

 of others. All the mouth and nasal discharges must be 

 carefully disinfected, carbolic acid being very useful for 

 this purpose. Disinfection should, of course, extend to 

 spoons, glasses, and other things coming in contact 

 with the mouth. When examining the throat it is well 

 to interpose a pane of glass between the patient and ex- 

 aminer, in order to safeguard the latter when the patient 



