DIPHTHERIA. 53 
noting each characteristic and comparing it with those 
described above. 
The beginner is strongly recommended to procure a 
series of slides of diphtheria bacilli from a bacterio- 
logical laboratory and to study them carefully. 
Hoffman’s bacillus (Plate I., fig. 2) is a modified 
form of the true diphtheria bacillus, and is frequently 
met with in throat cultures. It is about as long as 
the short form of diphtheria bacillus, but decidedly 
plumper and is more uniform in shape and _ size. 
These bacilli stain uniformly and deeply. They ex- 
hibit the same arrangement, and are often grouped in 
pairs. Clubbed forms do not occur. 
The diphtheria bacilli which occur in films made 
direct from the swab are similar to those seen in 
cultures, but are often thicker; they may stain uni- 
formly, and clubbed forms are rare. It is unusual to be 
able to make an absolute diagnosis as to their nature, 
but it may be done at times. Yet such an examination 
is often useful. If suspicious bacilli are present you 
should inject antitoxin forthwith; if no suspicious 
bacilli are seen it is safe to wait for the result of the 
cultural examination. 
INTERPRETATION OF RESULTS. 
The discovery of the diphtheria bacillus in the exudate may 
mean :— 
(a). That the patient is suffering from diphtheria. 
(b). That he has suffered from diphtheria and is now 
convalescent but is stil infectious. The bacilli may 
persist for weeks or months and while they do so the 
