422 B A CTERIOLOG Y. 



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. 



DIPHTHERIA ANTITOXIN. As stated above, the 

 growth of bacterium diphtherias is accompanied by the 

 elaboration of a poison of remarkable toxicity that is 

 accountable for the constitutional symptoms and patho- 

 logical lesions by which the disease is characterized. If 

 by appropriate methods this poison (toxin) be separated 

 from the bacteria by which it was formed, it is capable, 

 when injected into susceptible animals, of causing death 

 and practically all the lesions that accompany the dis- 

 ease when due to the invasion of the living bacteria. If, 

 on the contrary, the dose of poison be so adjusted as to 

 cause only temporary inconvenience and not endanger 

 life, and this dose be injected repeatedly, gradually in- 

 creasing in size as the animal is able to bear it, after a 

 while a marked tolerance is established, so that the animal 



