GENERAL SYSTEMATIC BACTERIOLOGY 479 



Thesing (1906, p. 351) takes exception to placing the spirochetes 

 among the protozoa, holding them to be typical bacteria, and Spiro- 

 chaeta to include all. 



Swellengrebel (1907, p. 582) gave the following diagnosis: 



Cellules san cils, avec appendice periplastique bien developpe et souvent 

 de structure alveolaire. Quelquefois, il y a une bande de myonemes dans I'appen- 

 dice. Type Spirochaeta plicatilis Ehrenberg. 



It will be noted that he excludes from the genus the forms parasitic 

 in higher animals. The genus Spirochaeta together with Treponema 

 and Borrelia are included together under the subfamily Spirochaetaceae 

 of the family Spirillaceae. He regarded the organisms as belonging 

 definitely with the bacteria. 



Dobell (1910, p. 536) restricts the generic designation Spirochaeta 

 to include only the groups closely resembling the original Spirochaeta 

 plicatilis Ehrenberg. The genus therefore includes only the free living 

 water or marine forms, all parasitic types being excluded. 



Zuelzer (1911, p. 51) after a careful study of Spirochaeta plicatilis 

 came to the same conclusion as Dobell — Spirochaeta includes the fresh 

 water and free living spirochetes; Cristispira, the mussel spirochetes; 

 and Treponema, the group of pathogenic forms. She defines the genus 

 Spirochaeta to include the strict anaerobic mesosaprophilic organisms, 

 Uving usually in the presence of H2S and growing well in the presence 

 of Beggiatoa. The organism is actively flexible, the protoplasm being 

 spirally wound around a straight elastic axis filament. In the plasma 

 spiral there regularly occur volutin granules. The plasma is naked, 

 that is, there is no differentiation of membrane or pariplast. The cell 

 is circular in cross section. The organism multiplies by transverse 

 fission. Three new species of Spirochaeta were described by this author. 



Bosanquet (1911, p. 69) includes all spirochaetes in the genus Spiro- 

 chaeta. This author is inchned to include these under the heading 

 of bacteria. Heim (1911, p. 252) lists the pathogenic forms under the 

 generic name Spirochaete with the species S. obermeierii. 



Doflein (1911, third edition, p. 351) used the generic name Spiro- 

 chaeta in two senses; in a limited sense, to include all slender spiral 

 organisms, and in a somewhat narrower sense, as a term to include 

 fresh water spirals and their near relatives, differentiating the genera 

 Cristispira and Treponema. 



Gross (1911, p. 109) has accepted the definition of Spirochaeta used 

 by Zuelzer and insisted upon the necessity for another generic name 



