282 



MANUAL OF BACTERIOLOGY. 



recognition with the microscope easy in most cases. The 

 growth, furthermore, is quite characteristic, and its nature 



can be predicted with consider- 

 able accuracy, even without mi- 

 croscopical examination, by one 

 who has had much practice. 

 Colonies of streptococci fre- 

 quently look very like those of 

 the bacillus of diphtheria, but 

 these two are easily distin- 

 guished from each other with 

 the microscope. The diagnosis 

 of the diphtheria bacillus, then, 

 is made from the character of 

 the growth upon blood-serum 

 and the microscopical exami- 

 nation, taking into account the 

 size and shape of the bacilli, 

 with the frequent occurrence 

 of irregular forms and the pe- 

 culiar irregularities in stain- 

 ing. In doubtful cases a sec- 

 ond culture should be made 

 from the throat. 



The very large number of 

 examinations that have been 

 made by various boards of 

 health, have shown that pseudo- 

 membranous inflammations of 

 the throat are sometimes caused 

 by streptococci alone, or by 

 They have also shown that the 

 diphtheria bacillus may persist in the throat for a long 



1 Bissell. .Ifedictil NeiVS, May 31, 1902; American Journal Medical 

 Sciences, February, 1903, Review of Work of Massachusetts Boards of 

 Health. 



Bacillus of diphtheria, culture 

 on glycerine-agar. 



other pyogenic bacteria. 1 



