H. B. Hftciiinson and J. Clayton 151 



at the present time. We therefore propose to refer to it for convenience 

 as a "sporoid" stage until more information respecting the affinity of 

 this to other organisms is obtained. 



Motility. Evidence of independent movement of the filamentous 

 form may be obtained from observation in hanging drop, although 

 care must be taken to avoid appreciable changes in temperature. 

 Organisms which are attached to portions of cellulose fibre display a 

 slow rotatory movement, while occasional cells proceed with a sinuous 

 action through the culture liquid. Occasionally, on the extreme edges 

 of the drop the central portion of the filament remains stationary but 

 the ends ate reflexed so that, according as to whether they move in the 

 same or opposite directions from the major axis, the outhne of the cell 

 assumes an O or S shape. The filamentous form, therefore, possesses 

 perfect flexibihty. Up to the present, we have been unable to demon- 

 strate the presence of flagella. 



Staining reactions. S. cijtophaga generally takes up the conventional 

 bacteriological stains with comparative tardiness. Methylene blue, 

 while faihng to give any satisfactory result with the filament form, 

 gives faint staining of the sporoids. The organism reacts negatively 

 towards Gram's stain and does not respond well to the action of dilute 

 fuchsin. The most satisfactory results obtained hitherto have been by 

 the use of hot carbol fuchsin, for upwards of a minute, without subsequent 

 differential treatment. Bold preparations may also be secured by a 

 "deposition" stain, i.e. either flooding the film with weak alcoholic 

 fuchsin, and after tilting the slide to remove the superfluous stain, 

 allowing the remaining solution to dry on the film or, alternatively, by 

 placing a cover-glass on the film, flooding the intermediate space with 

 the stain, and then quickly raising the cover-glass from one side. By this 

 means small quantities of solution are left in the immediate vicinity of 

 the cells, on which the residual stain is ultimately deposited. The staining 

 capacity of the organism varies greatly, however, with the cultural 

 conditions and occasionally even the most intensive methods fail to yield 

 satisfactory results. 



Spore formation. Spore formation in the ordinary sense of the term, 

 i.e. the production of a stage which possesses greater powers of resistance 

 to external factors, does not appear to take place with S. cytophaga. 

 Any other interpretation of the function of a spore as, for example, the 

 contention that spore production is nothing more or less than the 

 adoption of a resting stage, is difficult of application to the organism 

 under consideration. Although there is abundant evidence that the 



