522 Relapsing Fever 



thing caused by the same parasite, or whether they are dififerent 

 diseases caused by slightly different parasites. 



If Nuttall be correct, there are no adequate grounds upon which 

 to conclude that the spirochetes are really different species. On 

 this account, and as the differences between the organisms are 

 minute, it scarcely seems well to devote space to the consideration 

 of each, but better to select the oldest and the best known — Spiro- 

 chaeta recurrentis — as the type, describe it, and then point out suqh 

 variations as are shown by its close relations. 



Morphology.- — The Spirochseta recurrentis is extremely slender, 

 flexible, spirally coiled, like a corkscrew, and pointed at the ends. 



Fig. 199. — Spirochseta recurrentis (Novy). Rat blood No. 321a. X 1500. 



It measures approximately 1 fi in breadth and 10, 20, or even 40 /i 

 in length. The number of spiral coils varies from 6 to 20; the di- 

 ameter of the coils varies so greatly that scarcely any two are uni- 

 form. Wladimiroff * doubts the existence of a flagellum, but flagella- 

 like appendages are usually to be seen at one or both ends of the 

 organisms. An undulating membrane attached nearly the entire 

 length of the organism, very narrow, and inconspicuous, forms the 

 <;hief means of locomotion. The organism is actively motile, and 

 darts about in fresh blood with a double movement, consisting of 

 rotation about the long axis and serpentine flexions. No structure 

 ■can be made out by our present methods of staining and examining 

 the spirochseta. No spores are found. Multiplication is thought 

 to take place by longitudinal division, though some beUeve the di- 

 vision to be transverse. 



*"Kolle and Wassermann's Handbuch der pathogene Mikrobrganismen," 

 J903, ni, p. 82. 



