ox GRISTISrrU'A VENERIS NOV. SPEC. 5o7 



importance which is common to Spirochgets and FlageHates — - 

 save that both are unicelhilar. It is, to me, most remarkable 

 that anyone can see any real resembhince between a Spiro- 

 chaet and a Trypanosome. The nuclear and cytoplasmic 

 structures are wholly different : a Trypanosome lias a flagellum, 

 a Spirochast has none :^ the crista is not like an undulating 

 membrane: the cell-membranes are not similar: and moreover, 

 the method of division is quite different in the two groups of 

 organisms. As regards conjugation, nothing has been proved 

 either in Trypauosomes or Spirocha3ts, so that its occurrence 

 or non-occurrence can furnish no grounds for discussion of 

 affinities between the two groups. The flexibility of Spiro- 

 clitets also, as I have pointed out, affords no criterion for 

 determining their protozoal or bacterial affinities. 



Many workers regard the Spirocha^ts as Bacteria. Xovy 

 and Kuapp (190G) place them in the genus Spirillum. 

 Swellengrebel (1907) places the Spirochasts and Spirilla in 

 the same family (Spirillaceje) among the Bacteria. Schellack 



(1909) suggests that the Spirochasts are related to the 

 Cyanophycea3 by way of Spirulina and similar forms. Gross 



(1910) finally places Spirochi^ta with the Cyanophycete, 

 and Cristispira and Treponema with the Bacteria. Ziilzer 

 (19lOj, however^ who has made a special study of S. plica- 

 tilis and the spiral forms of CyauophycetB (Spirulina, 

 Arthrospira), has shown that there is no real siinilarity 

 between these organisms. Affinities between Spiroch;ets and 

 Cyanophycete appear therefore not to exist. 



Now beyond a certain superficial similarity of form between 

 certain Spiroch^ets and Spirilla, there is really no reason for 

 regarding Spirochsets as Bacteria. The points of similarity 

 are chiefly these — both possess the same sort of cell polarity 

 (see p. 532), both divide transversely, both are plasmoiysable. 



1 Tlie •• flagella" of various species of Treponema are probably — us 

 has often been pointed out already — merely the drawn-out ends of 

 organisms which have just resulted from the transverse division of a 

 longer organism. They have nothing to do with the flagella of Protozoa 

 or Bacteria. 



