Ward . — Some Thames Bacteria . 
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This was done, and several well-isolated rodlets were now 
found near the margin of the colony and clear of it. I now 
focussed a pair, lying close together but sufficiently apart 
for distinct observation : their position was fixed by means 
of the micrometer, and they were drawn at 10 a.m. ; the 
temperature being 21*5° C. 
Their behaviour at subsequent periods of observation is 
given in Figs. 16 a-f. At 30.20 each had divided, though 
the two halves were still joined: at 10.35 they were free, 
and now there were four rodlets in place of two (see Fig. 
16 e). At 1 1. 10 a left-hand rod was dividing, as shown by 
its biscuit-shape, and at 11.40 there were six rodlets; at 
12.20 a rod below, to the right, was dividing, and by 12.45 
there were eight rodlets. 
Now it was evident that in the successive divisions the 
sister-halves were not equally capable of dividing. The 
question arises whether this is due to position, or some other 
cause. I am strongly inclined to regard it as due to position ; 
in each case the new divisions occurred first in cells nearest 
new territory , i.e. advancing away from the colony into 
unexplored gelatine. 
The above observations had now to be interrupted, and 
on resuming them at 3.20 p.m. a startling discovery was 
made — all the free bacilli were in active swarming move - 
ments . The temperature had slowly risen to 23*5 and 
remained there, and the gelatine-drop had absorbed a great 
deal of water : these factors, taken with the liquefying 
power of the colony, explain why the drop was now 
liquid. 
But the swarming was an unexpected phenomenon. 
I had got over my surprise at the isolated rodlets, above 
described, showing no capsules, because earlier examina- 
tion of the gelatine colonies showed that not all the cocci 
or rodlets are capsuled. Hitherto, however, they had 
shown no signs of movements. The obvious suspicion 
arose that an intruding swarmer had got into my hanging- 
drop. 
