44 CLINICAL BACTERIOLOGY AND HiEMATOLOGY 



very thorough search ; if no bacilli are seen, make several more 

 films and examine them. When you see a group of bacilli, 

 examine it carefully, 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 bacteriological laboratory, and 

 to study them carefully. 



Hoffmann's bacillus (Plate I., Fig, 2) is probably 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 exhibit 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 uniformly, 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 con- 

 valescent, but is still infectious. The bacilli may persist for weeks 

 or months, and while they do so the patient must be isolated and 

 treated with antiseptic gargles. 



(c) That he is in danger of acquiring diphtheria if subjected 

 to any influence which lowers his vitality, or which would cause 

 ordinary sore throat in any ordinary person. 



(d) It always means that the person may communicate diphtheria 

 to a susceptible subject. 



The significance of Hoffmann's bacillus is not yet settled. It is 

 frequently found in the throat when the patient is convalescing 

 from an attack of diphtheria, and sometimes in subjects who after- 

 wards develop diphtheria. It also appears to cause epidemics of 

 sore throat which do not present anything remarkable in their 



