i 5 o SCIENCE PROGRESS 



have been asserted by some to be devoid of a nucleus, 

 though this is incorrect, for many Bacteria possess a diffuse 

 nucleus of scattered granules of chromatin. In the Spirochaetes, 

 as shown by recent researches, there is a spiral of chromatin 

 (fig. 2, c, d) running practically the whole length of the organism 

 (5, 6, 12). Such a distribution of chromatin represents a diffuse 

 nucleus. One of the largest of the Spirochaetes is S. balbianii 

 (fig. 2, a), 1 from the stomach, intestine, and crystalline style of 

 the oyster. Another species, S. anodontce, occurs similarly in 

 the alimentary tract of the pond-mussel (fig. 2, b). 



The presence of a spirally wound and undulating membrane 

 has already been mentioned. In S. balbianii this possesses a 

 thickened border (fig. 2, a) which colours deeply with chro- 

 matin stains and gives the general reactions of the substance 

 chromatin. Such a chromatic border is probably a constant 

 feature of Spirochaetes, but is not easily seen in the smaller 

 species. 



It is most instructive, though difficult, to follow the move- 

 ments of Spirochaetes under the microscope. This study of 

 movements is not only interesting, but is of economic im- 

 portance; for, as I hope to show in the sequel, it should be 

 possible to determine from its movements whether an organism 

 belongs to the genus Spirillum or Spirochceta. 



Researches of this nature require the examination of living 

 material, which tends to be very much overlooked or even 

 entirely ignored. It is not sufficient to rely on stained pre- 

 parations alone. For the observation of the living Spirochaete, 

 care must be taken to place it in its natural environment 

 as far as possible. It is useless to record the movements of 

 a parasite under unfavourable conditions, such as when its 

 host begins to react upon it. 



The movement of Spirochaetes has only been investigated 

 to any extent in the case of S. balbianii and 5. anodontce (5). 

 Each of these moves very rapidly, especially 5. anodontce, with 

 its pointed ends (fig. 2, b). It is almost impossible to analyse 

 their motion when moving at full speed. In the case of 

 slowly moving specimens, it is seen that the Spirochaete 

 moves forwards while rotating on its long axis. The move- 

 ment appears to be resolvable into at least two elements or 

 components : (i) a wave-like flexion of the body chiefly for 



1 First described by Certes as Trypanosoma balbianii in 1882. 



