RELAPSING FEVER. 179 



QUESTIONS. 



By whom and when was the Bacillus pestis discovered? 



Describe this bacillus. Its mode of staining. Its principal biologic char- 

 acters. 



What temperature suits its growth best? What is the effect of high tem- 

 perature ? 



How does it grow on gelatin ? On agar ? On bouillon ? 



What is its behavior with regard to fermentation aud to indol pro- 

 duction ? 



How does it affect milk? 



How is it affected by disinfectants? 



What animals are susceptible to this disease? 



How are inoculations performed ? 



Describe the symptoms and lesions caused by inoculation. 



What three forms of bubonic plague are recognized in man? Which is 

 the most frequent? Which the most fatal? 



How does infection take place? 



What are the symptoms of the disease, aud what the lesions in man ? 



How is immunity conferred in this disease? 



Does the serum in cases of plague contain agglutinating power? 



How does Yersin manufacture his protective serum? What does he claim 

 for it ? 



How does Haffkiue practise his protective inoculations? 



CHAPTER XXI. 

 RELAPSING FEVER. 



Spirillum Obermeieri. 



History. As early as 1873 Obermeier discovered in the 

 blood of patients suffering from relapsing fever a long, spi- 

 rillum-like microorganism, measuring from 20 to 30 mikrons, 

 having the power of active motion. His observations have 

 since been confirmed by a number of other investigators. 



This spirillum, which has not been cultivated artificially, is 

 found in the blood and spleen, but never in the secretions of 

 patients affected with relapsing fever. 



Morphology and Biology. It stains readily by all the anilin 

 dyes, but does not stain by Gram's method. It is actively 

 motile and contains no spores. 



In the blood it is found in two forms: (1) during the pyrexia 



