i 5 2 SCIENCE PROGRESS 



progression, and (ii) a corkscrew motion of the body as a 

 whole, due to the spiral winding of the membrane. Forms 

 with pointed ends, like S. anodontce, exhibit the corkscrew 

 motion very well, and easily bore their way through the 

 debris of cells floating in the gut contents of the host. 



The figures of 5. plicatilis of Ehrenberg strongly suggest 

 that it possesses a spiral motion, and small forms which I 

 have seen in pond-water, and which may be S. plicatilis, 

 support this view. 



While the organism is moving, waves can be seen travelling 

 down the thread-like body in a direction opposite to that in 

 which the organism is progressing. Many such waves are 

 seen passing down the body of rapidly moving forms, while few 

 4 .5ome two to four) waves occur in more slowly moving ones. 

 Very rapidly moving specimens appear almost straight, each of 

 the many undulations of the body being only slight. 



It is also interesting to observe that the movements occur in 

 jerks. A Spirochaete may suddenly come to a dead stop, or 

 just as suddenly proceed to move slowly. It does not seem to 

 matter in the least which end of the body is directed forwards, 

 for the organism is able suddenly to reverse its direction of 

 movement and to return on its own path, whether it be straight 

 line or circle. A Spirochaete, then, can move with or against 

 the current indifferently, and much energy seems to be used in 

 movement, though without very adverse effect on the normal 

 organism. It has been suggested by Novy in the case of 

 S. obermeieri that the retracing of the path is due to unfavourable 

 environment. This is, I think, doubtful, if not incorrect, for I 

 have observed both S. anodontce and 5. balbianii constantly 

 retracing their path in the crystalline style of their bivalve 

 hosts. 



When the Spirochaete appears suddenly from the deeper 

 levels of the liquid under examination, it is seen to bore its 

 way more or less vertically upwards, twisting itself into various 

 complex shapes, forming very beautiful figures such as Catherine 

 wheels, but sometimes almost bewildering to watch or to ana- 

 lyse. If one end of such a parasite be anchored to debris, the 

 free end is seen to execute violent lashing movements. Slowly 

 moving specimens frequently curl up one end. To sum up as 

 regards movements, Spirochaetes seem to move more quickly 

 than Trypanosomes, and with an added corkscrew motion. Their 



