CLASSIFICATION OF THE MAIN SUBDIVISIONS 469 



respect between spirochaetes and trypanosomes and other flagellates. In the 

 words of Dobell, " the nuclear and cytoplasmic structures are wholly different ; 

 a trypanosome has a flagellum, a spirochaete has none ; the crista is not an 

 undulating membrane ; the cell-membranes are not similar ; and, moreover, 

 the method of division is quite different in the two organisms." 



Doflein (7) places the spirochsetes as a group named the Pro- 

 flagellata, supposed to be transitional from bacteria to flagellates. 

 Zuelzer (904) takes a similar view, rejecting, however, any affinity 

 between spirochsetes and Hartmann's " Binucleata." Awerinzew 

 (890) puts forward the remarkable suggestion that the Flagellata 

 " pass on into different Binucleata, and end with the Spirochceta 



FIG. 194. Stages in the division of Cristispira pcctinis. A, B, Two successive 

 stages of the incurvation ; 0, incurvation complete ; D, division of the body 

 at the point where it is bent back ; E, F, separation of the two daughter- 

 spirochsBtes. After Gross (897). 



(sic)" from which it would appear that he regards the spirochsetes 

 as the last product of the line of evolution that produced the 

 trypanosomes and allied forms. 



For the various reasons that have been set forth above, it appears 

 impossible to include the spirochsetes any longer in the Protozoa. 

 Dobell regards them as "an independent group of unicellular 

 organisms which show very little affinity to any other group." 

 Gross, on the other hand, considers that the Spironemacea i.e., 

 the genera Cristispira, Saprospira, and Spironema, in the sense in 

 which this genus is understood by him (see above) form a family 

 which can be ranked in the bacteria, but which is related to the 

 Cyanophycese, especially the Oscillatorise. 



