RELAPSING FEVER. 447 



needle into the swelling. The fluid is then to be examined 

 microscopically, and cultures on agar or blood serum should be 

 made by the successive stroke method. The cultural and mor- 

 phological characters are then to be investigated, the most impor- 

 tant being the involution forms on salt agar and the stalactite 

 growth in bouillon, though the latter may not always be obtained 

 with the plague bacillus ; the pathogenic properties should also 

 be studied, the guinea-pig being on the whole most suitable for 

 subcutaneous inoculation. In many cases a diagnosis may be 

 made by microscopic examination alone, as in no other known 

 condition than plague do bacilli with the morphological char- 

 acters of the^ plague bacillus occur in the lymphatic glands. An 

 examination of the blood will only give positive results in severe 

 cases. And in every instance, on the occurrence of the first 

 suspected case, every care to exclude possibility of doubt should 

 be used before a positive opinion is' given. 



In a case of suspected plague pneumonia, in addition to 

 microscopic examination of the sputum, the above cultural 

 methods along with animal inoculation with the sputum should 

 be carried out; subcutaneous injection in the guinea-pig and 

 smearing the nasal mucous membrane of the rat may be recom- 

 mended. Here a positive diagnosis should not be attempted by 

 microscopic examination alone, especially in a plague-free dis- 

 trict, as bacilli morphologically resembling the plague organism 

 may occur in the sputum in other conditions. 



RELAPSING FEVER. 



At a comparatively early date, namely in 1873, when practi- 

 cally nothing was known with regard to the production of disease 

 by bacteria, a highly characteristic organism was discovered in 

 the blood of patients suffering from relapsing fever. This discov- 

 ery was made by Obermeier, and the organism is usually known 

 as the spirillum or spirochate Obermeieri, or the spirillum of 

 relapsing fever. He described its microscopical characters, and 

 found that its presence in the blood had a definite relation to 

 the time of the fever, as the organism rapidly disappeared about 

 the time of the crisis, and reappeared when a relapse occurred. 

 He failed to find such an organism in any other disease. His 

 observations were fully confirmed, and his views as to its causal 

 relationship to the disease were generally accepted. Later, the 



