SYSTEMATIC DESCRIPTION OF SPECIES. 



75 



ments being thus produced. A streaming of protoplasm 

 may be seen. There is no undulating membrane or 

 distinct periplast. The axial thread is important for 

 classification. Sp. plicatilis may be found in the sea 

 (Naples) as well as in fresh water. The organism is 

 dissolved by trypsin. 



As Sp. plicatilis is the "type species " and other spiro- 

 chaetes must justify their inclusion in the genus by their 



FIG. 59. Diagrammatic representations of Spirochaeta plicatilis; 



a, according to Zuelzer, straight central rod and dots in the curls; 



b, after Schaudinn, central rod follows the curves, dots superposed 

 on it at random; c, after Doflein, double series of curls with cor- 

 responding dots and indications of central rod; d, imaginary 

 figure showing central rod corresponding with dots in the diagram 



resemblance to this, it is unfortunate that so great a 

 diversity obtains between the descriptions given by 

 various writers. Thus the organism is flat (Schaudinn, 

 Doflein) , round (Zuelzer) ; it has a double series of curls, 

 smaller and larger (Doflein) , a single series (Zuelzer) ; 

 its axial filament follows the curves of the organism 

 (Schaudinn) ; it runs in a straight line (Zuelzer) . These 

 differences are illustrated in the accompanying dia- 



