BRIEF NOTES ON SPIR0CHJ<;TA ANODONT-E keysselttz. 389 



the same spirochaete may present different shapes and sizes. 

 I have never seen specimens of Sp. anodontas with trans- 

 verse lines near the middle of the length of the organism, 

 pointing to transverse division by means of a septum here 

 formed, as is depicted by Schellack. 



As to the actual method of division, 1 had the opportunity 

 of observing an instance of what appeared to be longitudinal 

 fission. This was in a preparation containing living spiro- 

 chastes in a drop of fluid from the mantle-cavity of the 

 mussel. My attention was attracted to an individual which 

 remained fixed at one point, near to the edge of the prepara- 

 tion, and Avriggled feebly, instead of dashing about like the 

 others. I then noticed that this spirochaete seemed to 

 possess two " tails/' if this expression is allowable (fig. Ha) ; 

 and on watching it I noticed that a line, dark at one moment, 

 refringeut at anothei', as the creature moved, was gradually 

 extending along the body of the spirochaate from the point 

 of bifurcation towards the opposite extremity. Fission pro- 

 ceeded along this line, but not quite regularly as in tearing 

 a strip of calico, since at one moment there was visible a sort 

 of loop in the "anterior" part of the organism — using this 

 term for the portion which remained single longest — before 

 the process of division had extended quite to this point from 

 "behind'' (6gs. ll/:>, c). AV^hen the longitudinal fissure had 

 extended nearly to the " anterior " end, the organism sud- 

 denly jerked itself away out of the field of the microscope- 

 and I was unable to see the final separation of the daughter, 

 individuals ; but as I was unable, on searching through the 

 preparation, to find the dividing spirochaete again, I could 

 only conclude that the separation took place almost imme- 

 diately, the two resulting spirochetes being then indistin- 

 guishable from the other individuals present. 



A possible source of error in this observation lies in the 

 slenderness of the organisms and in the difficulty of accurately 

 observing them during movement. It is scarcely possible to 

 exclude the explanation that an organism may become folded 

 upon itself as a preliminary to undergoing transverse fission 



