CHAPTER XXV. 

 SPIROCH.ETVE. 



Spirochaeta Plicatilis. Ehrenberg in 1833 observed this long 

 slender spiral organism in swamp water. It occurs commonly 

 in stagnant water among the algae which grow there and has also 

 been found in sea water. The cell is about 0.75/4 in thickness and 

 20 to 500/1 in length. It moves by rotation and also by bending 

 of the thread. Multiplication takes place by transverse division, 

 sometimes occurring simultaneously at many points in a filament 

 so that many short forms result. This organism is regarded as 

 the type species of the genus Spirochceta. 



A number of saprophytic spirochetes are known. Dobell 1 

 has made a careful study of several species, not only free-living 

 but also parasitic spirochetes, directing special attention to their 

 systematic relationships. He concludes that the spirochetes 

 belong to the bacteria and that they agree with the bacteria in 

 their structure in all respects except the organs of locomotion. 

 Concerning the flagella he seems to be doubtful. 



Spirochaeta Recurrentis. Obermeier in 1873 described the 

 slender spiral organism first seen by him in 1868 in the blood in 

 cases of relapsing fever. Ross and Milne observed a similar 

 organism in man in Uganda in 1904 and Button and Todd in the 

 same year demonstrated the presence of a spirochete in the blood 

 in the African tick fever of the Congo. In 1905 a similar organ- 

 ism was found in a case of relapsing fever in New York City. 

 The disease has also been recognized in Russia and in India. 

 The spirochetes have been successfully inoculated into monkeys 

 and into rats, and various strains from different parts of the 

 world have thus been made available for comparative study in 



1 Archiv.f. Protistenkunde, 1912, Bd. XXVI, pp. 117-240. 

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