Ward. — Thames Bacteria, III. 207 
which straighten to rays as they approach the periphery and 
give the whole colony a curious resemblance to an Acineta. 
(See Fig. 12.) 
But more careful observation — and easily overlooked, as it 
was by myself at first — shows that beyond the radiating 
tresses is an extremely tenuous and hyaline irregularly lobed 
coronal film on the surface of the gelatine, and formed by the 
radiating tresses as they emerge. Liquefaction rapidly sets 
in towards the end of the second day, and the plate is usually 
destroyed by the third day. 
The liquefaction differs in character from that of most 
common liquefying Bacteria, and does not consist in a scoop- 
ing out of the gelatine in circles and throughout its depth, 
but is universal over the surface of the plate only ; even on 
the fourth day the lower parts of the film may be firm. 
Unlike the ordinary cases also, the watery liquid has a very 
slight odour, not decidedly unpleasant. 
One of the most remarkable features about these plate- 
cultures at 20° and near that temperature, was the extremely 
rapid liquefaction that sets in towards the end of the second 
day, and for some time I was excessively puzzled by this 
phenomenon. Over and over again I left a plate looking 
quite ‘safe* at 8 or 9 p.m., to find it liquefied all over next 
morning. Several times I have visited the plates at various 
hours between midnight and 4 a.m. with the same result ; the 
plates looked quite ‘ safe/ with colonies only 4 or 5 mm. in 
diameter, and yet by 8 or 9 a.m. they had liquefied. 
One point struck me, and eventually gave the clue to the 
explanation. When the liquefaction was observed carefully 
next morning, one saw that it was at first only superficial ; 
the whole top-layer of gelatine was a watery liquid, but the 
gelatine below was still firm and had its colonies firmly 
imbedded. 
Then — by an accident in the first case — I found that just 
before the sudden liquefaction, if the plates were held 
obliquely to the light of a lamp, a faint iridescent shimmer 
is to be discovered around .each of the emerged colonies, 
