Ward. — Thames Bacteria , III. 
227 
colonies are irregular cloudy aggregates ; others still preserve 
the zoned and sieve-like appearance to some extent. Colour 
more yellow and colonies sinking or running. In a week the 
circular colony (15 mm. diameter) is composed of bright ochre 
cloudy masses floating in the lens of liquefaction, and this is 
surrounded by a nearly colourless zone of radiating tresses in 
the still solid gelatine, and with floating ‘ islands ’ on the 
surface around. 
The most extraordinary feature in all these colonies, how- 
ever, is the formation of the primary tresses — the serpentine 
central tresses referred to above. These are in reality 
compact zoogloea-masses composed of numerous twisted 
tresses, the walls of which swell and hold the whole together, 
forming the curious dumb-bell-shaped or jointed or serpen- 
tine masses referred to. The thinner and thinner tresses 
which radiate out from these become more and more tenuous 
as the filaments remain isolated and break up into rows of 
segments or free Bacilli. 
Later on one finds that many of these at first almost free 
filaments can also become intertwined to serpentine zoogloea- 
masses, and the Figs. [36-38] give examples of the various 
ways in which this can come about : it appears to depend on 
the submergence in the gelatine. 
The explanation of this phenomenon in detail is difficult, 
but there can be no doubt that these zoogloea-tresses are the 
same as those figured by Hauser in his monograph on ‘Faul- 
nissbakterien,’ as seen in the various forms of Proteus , and as 
those described on pp. 207-214 above. 
The following observations throw more light on this 
subject. 
A rodlet isolated in 5 per cent, gelatine was fixed at 20° 
under the immersion at 9.20 a.m. (Fig. 39 a). At 11 o’clock 
it had grown to nearly three times its original length, and 
divided once (Fig. 39 b). At u.50 each of the two rodlets 
had slipped a little past the other, and one of them had 
divided again ( c ). At 12.30 there were four rodlets, two still 
in connexion, the other two free (d). At 5 p.m. a small 
