SPIROCHATA BALBIANII AND SPIROCHATA ANODONTA. 17 
a circle, while motion along paths forming complex geometric 
figures, as helices, figures of 8, and Catherine wheels also 
occurs (text-fig. 4, and Pl. 1, fig. 6). These figures are 
often of great beauty in spite of their complexity, and an 
organism executing them is most interesting, yet bewildering, 
to watch: Lashing movements are also seen sometimes. 
In the case of slowly moving specimens it is seen that the 
organism moves forward while turning on its long axis. 
The motion appears to be resolvable into at least two com- 
ponents: (i) An undulatory flexion of the body, mainly for 
progression, and (11) a spiral or corkscrew movement of the 
body as a whole, due to the winding of the membrane. The 
corkscrew motion is especially well seen in the case of 
LAN 
TExt-FIG. ]1.—The outline of the sinuosities of the moving organ- 
ism is a little irregular. The contour of the waves is broken by 
smaller waves, though in the lower figure this is somewhat 
exaggerated. 
_S. anodonte, and is probably to be correlated with its 
possession of pointed ends. The spiral motion, in the case of 
S. balbianil, is not at first sight very apparent in all speci- 
mens, and its ends are blunt. 
Waves can be seen travelling down the thread-like body in 
a direction opposite to that in which the organism is pro- 
gressing. Many waves or sinuosities, some eight or ten, or 
even fourteen, can be seen along the body of rapidly moving 
forms, while only some two to four may occur along the body 
in more slowly moving organisms. The outline of the sinu- 
osities 1s sometimes a little irregular—that is, the contour of 
these waves is somewhat broken by much smaller waves 
(text-fig. 1). 
The movements occur in jerks. The organism may suddenly 
VOL. 52, PART 1.—NEW SERIES. 2 
