CH. X.—MORPHOLOGY OF THE BACTERIA.—ARTHROSPOROUS BACTERIA. 471 
Beggiatoa alba (Figs. 197,198) forms filaments which in an intact state are attached 
in an erect position to fixed objects in dirty water, in water discharged from factories, 
andin hotsulphursprings. 
The filaments vary in 
thickness from 1 to more 
than 5 a, and consist of 
a single row of cells, the 
protoplasm of which con- 
tains granules of sulphur 
in quantities differing in 
each cell (see page 455) ; 
when the sulphur is very 
abundant it may be diffi- 
cult to perceive the boun- 
daries between the cells. 
The filaments have no 
separate common sheath 
and readily divide trans- 
versely into pieces. Their 
cells pass successively 
from the lengthened rod- 
form into the isodiametric 
form, and these in the 
case of the thicker fila- 
mentsinto flat discs which 
finally divide by longitu- 
dinal walls into four quad- 
rants (Fig. 127, 6-8). 
The disc-like cells as 
well as the isodiametric 
members of the slender 
filaments separate after 
a time from one another 
(Fig. 197, 9) and round 
themselves off, and then 
become active swarm- 
cells (Fig. 197, 10); at 

FIG. 197. Beggiatoa alba. 1 group of 2-5 of 
length they come to rest of different stoutness, 5 in the act of breaking up into fragments. The small dark circles in 

the interior are granules of sulphur ; in the parts of the filaments where the granules are 
and attach themselves to ern in sulphur ;h g the ponds ee Bar 
fixed objects. Theymul- Frans ii, 2 aid drin ae dem ere aber 
tiply abundantly by bi- > era 2 en A = in all cases granules of sulphur. After Zopf. 


partition and form irregu- 
larly-shaped zoogloea-heaps. They may also develope into rods and these again 
into the filaments above described after the rods have in many cases themselves 
passed through the swarming-state. In this species also spirally twisted filaments 
are found as well as the straight ones which we have been hitherto considering, 
