CAUSING ACtJTE INFECTIONS. 
91 
may be due to infection with micro-organisms other 
than the diphtheria bacilli, such as the staphylococcus 
and streptococcus. In order to say whether a mem¬ 
brane is due to diphtheria or not, a sterile cotton swab 
is rubbed over the membrane, and then rubbed on the 
surface of a tube containing coagulated blood-serum. 
The tube and swab are now sent to the laboratory and 
incubated at body temperature from twelve to twenty- 
four hours in order to allow the bacteria present to 
multiply. The growth is now smeared on glass slides, 
Fig. 11.—Bacillus diphtherise. X1000. (Drawing 
by E. L. Oatman, M.D .) 
