170 ROYAL SOCIETY OF CANAUA 



The heavy ring of growth at the surface and also the film consists 

 of small rods bomid by the mucilage which they excrete. When a piece 

 of growth is teased in water and examined, some swiftly motile cells are 

 seen and some rotate slowly or rapidly without liberating themselve' 

 from the entangled slime. (See photograph 34). 



The turbid liquid from the body of the culture shows some swiftl} 

 motile cells and others not in motion, also cells of irregular form, elong- 

 ated, bent or curved with one end swollen or forking. Twice and thrice 

 branched cells occur (see photographs 2 G and 33). Extravagant forms 

 with the branches swollen or elongated are not infrequent (see photo- 

 graphs 29 and 34). 



The slimy sediment consists of cells entangled in a mesh of slime 

 threads. Small rods occur but branched and irregular forms usually 

 prevail. 



8. Staining Reactions. Flagella Stain. Take a loop of the muci- 

 laginous or viscid growth from an agar culture two days to several 

 months old and spread it on a clean slide, lashing it out in slender ton- 

 gues, let the film dry in air without killing or fixing, flood the film a 

 moment with a saturated alcoholic solution of gentian violet, Avash unde • 

 the tap, dry between folds of filter paper and examine with the oil ini- 

 m.ersion lens. The mucilage in which the cells lie will be found deeply 

 and evenly stained and the bacteria scarcely . stained at all, so that the 

 preparation presents the appearance of a photographic negative. The 

 unequal density of the protoplasm of the cells is clearly seen, as indeed 

 it is in the living cells when examined in a hanging drop, (see photo- 

 graphs 27 and 31). 



The single polar flagellum is clearly demonstrated by this stain since 

 it, like the protoplasm of the cells, refuses the stain, and so it appears as 

 a clear or uncoloured streak in the surrounding, deeply stained, mucilage. 

 The flagella are best seen at the margins of the film and in thin places. 

 «'See photographs 27 and 31). In parts of the film where the culture 

 is thickly spread, the mucilage is intensely stained and the flagella being 

 slender and enveloped deeply in the mucilage, are not distinguished. 

 In these parts, however, the cells are beautifully contrasted with the dark 

 background and their internal structure is clearly shown. Saturated al- 

 coholic solution of methyl blue, night blue or fuchsin may be used in 

 place of sati;rated alcoholic gentian violet. A film prepared and stained 

 as above, then flooded an instant with Lugol's solution, is still more in- 

 tensely and darkly stained. 



Yoimg agar cultures stain well with carbolic fuchsin. The muci- 

 lage is not deeply stained, but the cells take the stain well and show the 

 irregular density of their protoplasm by its banded appearance. If thi 



