SPIROCHETE GROUP 443 



the flagellum all associated the organism with the bacteria. Bonel, 

 Frankel, and others claim to have demonstrated the presence of 

 numerous peritrichic flagella on certain forms, a condition which 

 is different from any known protozoan. As before stated, there 

 is so much discordance in the published work of the various in- 

 vestigators that definite conclusions cannot be reached. It has 

 been suggested that these organisms form a group intermediate 

 between the bacteria and the protozoa. This is not as probable as 

 has been sometimes urged, and such a disposition is simply a con- 

 fession of our lack of definite knowledge. It is by no means 

 improbable that some species of this group will be found to belong 

 to the bacteria and others to the protozoa, and that supposed 

 homologies are only superficial resemblances. 



Certain species have been removed from the genus Spirochaeta 

 and new genera created for them by certain authors. These 

 names are so common in literature that their meaning should be 

 known. It may here be again emphasized that the name Spiro- 

 chceta, as used in the discussion of the various species below, 

 includes all of these genera. 



Spirochceta (In Narrow Sense). Organism with an exceedingly 

 slender, spiral, flattened body, with a narrow, undulating membrane 

 that surrounds the entire body in a spiral. Xo flagella and no 

 spores are produced. Reproduction probably occurs by longi- 

 tudinal division. 



Spiroschaudinnia. Blood parasites. Minute wavy or spiral 

 threads, with undulating membrane and no flagella. Free motile 

 stage alternates with a stage in which the organism is coiled up 

 in one of the host-cells. Developmental stages have been demon- 

 strated in the intermediate host. The life-history is imperfectly 

 known. 



Treponema. Spiral body, not flattened, tapering at the ends. 

 Flagellum at each pole. No undulating membrane. Multiplica- 

 tion by longitudinal division. Does not stain with common 

 aqueous anilin dyes: special staining methods are required. 



The following organisms described as belonging to this group 

 are of sufficient economic importance to warrant their con- 

 sideration here: Spirochceta obermeieri, Sp. duttoni, Sp. pal- 

 lida, Sp. pertenius, in man; Sp. anserina (Sp. gallinarwn), in 



