No. 49S] 



THE SPIIKH HETES 



But even after these forms have been removed 

 Blanehard's original list of the genus Spin><h«t<i still 

 shows an unnatural mixture of varied forms. Among 

 the remaining species are undoubtedly those which form 

 other natural groups and will later be assigned to new 

 genera; but in the absence of fuller knowledge they mav 

 preferably be left for the present in the old genu>. No 

 doubt new forms will be added to this list. In this con- 

 nection attention should be called to yellow fever and the 

 view often expressed that the yet unknown cause of this 

 disease will also prove to be a spirochete. Similarly the 

 Miami disease of Persia known to be transmitted by a 

 bird tick, Argas persicus, and other tick diseases in 

 tropical and subtropical countries are thought to be due 



Only two weeks later than the publication by Blanchard 

 appeared an extensive paper by Novy and Knapp (1906). 

 These authors recorded studies on a spirochete from a 

 case of relapsing fever which was observed in Bellevue 

 Hospital, New York. They regarded this form as iden- 

 tical with S. recurrentis and as the result of most careful 

 studies reached the conclusion that the organism in ques- 

 tion was undoubtedly a bacterium and not a protozoon. 



and fail to indicate any trace of bodies which might be 

 interpreted as nucleus, blepharoplast, or undulating mem- 

 brane. They indicate also the presence of a single 

 flagellum at one end of the spiral about as long as the 

 spiral itself and with wavy turns corresponding in gen- 

 eral to those of the spirochete, while a short process occurs 

 at the other end. The staining qualities of the flagellum, 

 the action of the organism under the influence of 

 plasmolytic changes, its behavior both during and after 

 being killed by heat and also the persistence of the spiral 

 form under the most varied injurious conditions, are in 

 compatible, in their opinion, with a protozoan nature and 

 indicate affinity to the bacteria. The readiness with 

 which these authors established active immunity is of- 



