BACTERIUM XEROSIS. 409 



theritic and from innocent sore-throats are any organ- 

 isms almost constantly present ? Which are they, and 

 what are their characteristics ? 



Which are the predominating organisms in the an- 

 ginas of scarlet fever? 



Do these organisms simulate, in their cultural and 

 morphological peculiarities, any of the diiferent species 

 with which you have been working ? 



Do the diphtheria organisms disappear from the throat 

 with the disappearance of the membrane ? How long 

 do they persist? When obtained from the throats of 

 convalescents are they still pathogenic for guinea-pigs ? 



Prepare a bouillon culture of virulent bacillus diph- 

 theria ; after it has been growing for thirty-six hours 

 at 37-30 C. inoculate a guinea-pig subcutaneously 

 with about 0.1 c.c. of it. If the animal dies, note care- 

 fully the findings at autopsy, especially the distribution 

 of the bacilli. Now add to this culture sufficient pure 

 carbolic acid or trikresol to kill all bacteria in it, and 

 inject under the skin of another guinea-pig varying 

 amounts of the culture so treated, beginning with 0.05 

 c.c. ; determine the minimum fatal dose, and note in 

 which respects the post-mortem findings simulate and 

 in which they differ from those of the first animal. 

 Should any of the animals survive the injections of the 

 disinfected culture, note carefully their condition from 

 day to day, particularly any fluctuations in weight. 

 When they have quite recovered inoculate them with 

 living, virulent diphtheria organisms. Do the results 

 correspond with those obtained with guinea-pigs that 

 have never been treated at all ? Explain the results. 



