RELAPSING FEVER. 177 



Among these we may include the blood spirochaetes and the organism 

 of syphilis, which have many resemblances to the spiral form of bac- 

 teria, together with the three genera in which protozoal characteristics 

 are marked, namely, Leishmania, Trypanosoma and Trypanoplasma. 

 In addition we have flagellates in the intestinal canal and in the vaginal 

 secretion. Some authors place the genus Piroplasma with the flagel- 

 lates and there has been controversy concerning the nature of certain 

 projections from these bodies. It would seem preferably however, to 

 consider them under the sporozoa. 



FIG. 57. Spirilla of relapsing fever from blood of a man. 

 (Kolle and Wassermann.) 



Spirochaeta. 



The generic term Spirochaeta is applied to flagellates having a 

 spiral shape, an undulating membrane and no flagella. This genus is 

 one about which there are two views: one, that the members belong to 

 the bacteria; the other, that they are protozoa. The absence of 

 demonstrable nucleus and blepharoplast make them apparently 

 vegetable in nature while the variations in thickness, the fact of trans- 

 mission by an arthropod and indications of a longitudinal, rather than 

 a transverse division, would indicate protozoal affinities. 



S. recurrentis. This is the organism of relapsing fever. It was 



