ESSAYS ON BACTERIOLOGY. 135 



growth precedes that of other bacteria which may be 

 present, often being recognizable in eight to twelve 

 hours. A particle of this growth, removed from the 

 tube and stained, reveals under the microscope the 

 characteristic picture of the diphtheria bacilli. 

 Scraping off with a sterilized wire or cotton swab a 

 small amount of the membrane from the throat or 

 other seat of disease, rubbing it onto the culture ma- 

 terial, and placing the latter in the incubator, the di- 

 agnosis can usually be settled in twleve or at most 

 twenty-four hoiu's. Such cultures may also be made, 

 though more slowly, by keeping the tubes in any 

 warm place, as near a stove or furnace register, and 

 upon any of the ordinary culture media. But for 

 rapid diagnosis blood serum is necessary. Should 

 questions arise as to the accuracy of such diagnosis or 

 the virulence of the microbes, they may be settled by 

 inoculations upon animals. The discovery of the spe- 

 cific diphtheria germ, and of methods of ready recog' 

 nition, has resulted in establishing the fact that what 

 has been called membranous croup is usually laryn- 

 geal diphtheria, and that there are many cases of ex- 

 udative sore throat resembling diphtheria, some here- 

 tofore tentatively distinguished and some not, which 

 are due to other causes. It therefore affords a wel- 

 come means of eliminating hitherto unavoidable un- 

 certainty or error from reputable practice, and impo- 

 sition from respectable charlatanism. 



While the peculiar bodies found in the blood, and 



