SPIROCH^TES : STRUCTURE 



67 



impart steadiness to the motion. It is traversed 

 by contractile elements known as myonemes 

 (Fig. 18, d), and myonemes may 

 also be present in the body itself. 

 They are most important, since 

 it is by the action of the myo- 

 nemes that the movement of 

 the organism is brought about. 

 Bordering the membrane is a 

 noticeable, thickened myoneme 

 forming a chromatic margin. 

 The membrane extends the whole 

 length of the body, but the chro- 

 matic border is not continued as a 

 free flagellum. At each end of 

 the organism is a small, roundish, 

 basal granule (Fig. 18, a) or small 

 polar cap. Extending through 

 the body of the organism is a 

 series of barlike chromatin masses 

 (Fig. 18, 6), which represent the 

 nucleus. As the nuclear material 

 is thus scattered, the nucleus is 



said to be diffuse. The appear- T 



... . . f ,., FIG. 18 SPIROCH^TA 



ance of this nucleus varies in life, BALSIANH, FROM THE 



displaying slightly different ap- YSTER 

 pearances according to the phase a v Bas ^ g ranule ; b > 



bars 01 chromatin ; c, 

 through which the spirochaete is membrane; d, myo- 



passing at the time when exam- 

 ined. The appearances described 

 hereafter have been observed by 

 us repeatedly in living spirochsetes from molluscs, 



nemes in membrane. 

 Two slight myonemes 

 are also present on 

 the body 



