CHAPTER X.—MORPHOLOGF OF THE BACTERIA. :457 
vinegar, and Scheibler and Durin ! that those of Leuconostoc mesenterioides, were 
chiefly composed of the carbohydrate which comes nearest to cellulose; but it 
appears probable from the researches of Nencki and Schaffer? that in the gelatinous 
masses (zoogloeae) of purtrefactive Bacteria it consists chiefly of the albuminoid 
compound which is the principal constituent of the protoplasm of the cell, and to 
which these writers have given the name of mycoprofein, in combination with 
infinitesimal quantities of cellulose-like substance. I speak of this as probable only, 
because it is always a little doubtful how far the substances discovered by 
macrochemical examination have belonged to the one or the other portion of these 
minute bodies. 
The membranes are in very many cases colourless; but in some instances, as 
has been already said, it is supposed that the intense blue, red, and other hues assumed 
by some bacteria-masses, and due to colouring-matters resembling anilin dyes, do 
really belong to the gelatinous membranes, provided they are not excretory products 
which have found their way into the substratum®. The sheaths round the filament of 
Cladothrix and Crenothrix are-often rust-coloured or dark brown from the presence of 
ferrous hydrate disseminated through their substance. 
Many forms of Bacteria have the free movement of swarm-cells in fluids. 
Their rapid forward motion is- accompanied with rotation round their longitudinal 
axis, and in many cases with apparent curvature of their bodies, But many observa- 
tions under the most favourable circumstances have failed to detect in these forms 
anything like a distinct organ of locomotion. There are however other swarming 
forms in which extremely delicate filiform processes described as cilia or ‘flagella’ 
have been observed since Cohn’s, or even perhaps since Ehrenberg’s time; these 
processes appear at one or both extremities, one usually but sometimes two or even 
three together, proceeding from the same point. It would appear to be uncertain 
whether these formations, like the cilia of other vegetable swarm-cells, are parts and 
processes of the protoplasm and project through the membrane, or whether they 
belong to, and are appendages of the membrane itself. The grounds which Van 
Tieghem * alleges for the latter view, namely that no direct connection can be traced 
between these processes and the protoplasm of the cell, while they behave towards 
colouring reagents in the same way as the membrane and not as the protoplasm, are 
against their being true cilia. It is to say the least questionable whether they 
function as organs of locomotion, considering the irregularity of their occurrence in 
the forms which are endowed with motion; and it would also be well to enquire 
whether the so-called flagella or cilia may not vary in character according to the 
species, and belong in some instances, as for example in Bacillus subtilis, to the 
membrane, in others, as in the larger arthrosporous species, to the protoplasmi. 
According to the shapes in which they appease in the vegetative states a series 
of principal forms are distinguished :— 

+ See Van Tieghem in Ann. d. sc. nat. ser. 6, VII, p. 180. 
2 Journ. f. pract. Chemie, neue Folge, 20 (1879), p. 443. 
3 See Schröter, Ueber einige durch Bacterien gebildete Pigmente, and Cohn’s Beiträge z. Biol., 
Heft 2, p. 109; also Nägeli, Untersuch. ii. niedere Pilze, p. 20. 
* Bull. Soc. Bot. de France, XX VI (1879), p. 37- 
