106 MR. W. G. P. ELLIS ON A TRICHODERMA 
readily identified as an opaque cloudy spot on the clear jelly. 
This area extended, and with a lens a mycelium could be made 
out which penetrated deeper and deeper into the jelly, so that it 
appeared to contain a sunk cup filled with mycelium. The 
gelatine was liquefied in the neighbourhood of the mycelium, and 
beyond the circular margin of the liquid the mycelium could be 
seen growing in, and at the surface of, the gelatine until the 
whole contents of the tube or flask were liquid supporting a mat 
of mycelium at its surface. This liquefaction extended during 
the week, and by the tenth day there appeared on the surface of 
the gelatine white patches, at first very small, then about the size 
of small pin-heads, and growing until they were 2 mm. or more 
in diameter, still retaining their original white colour. In about 
a fortnight these white patches became yellowish in colour, 
deepening to a dull orange and then to a dirty grey, which 
became bluish and greenish ; later the patch presented a green 
centre surrounded by a white or greyish margin. When teased, 
they resembled the patches formed on the host in all essential 
particulars. Later on, that is to say by the end of the third week, 
the patch had become quite brown, though the margin remained, 
as a rule, the dull grey of the whole of the younger patch. No 
further change was noticed during eight weeks beyond the fact 
that fresh clusters appeared to grow out from the margin, 80 
that in old cultures the outline of the cluster was very irregular. 
The above differed somewhat from the formation of the clusters 
on the host itself. This is well shown by a comparison of two 
cases. In case (1) a piece of diseased thallus was isolated and 
kept covered in a glass dish on the laboratory-bench among the 
flask- and tube-cultures, and therefore exposed to the same con- 
ditions of temperature, &c. On Monday, June Ist, mycelium 
could be faintly seen growing over the surface, recalling the 
cobweb appearance mentioned earlier (p. 104). On Thursday, 
June 4th, the white patches appeared and were turning blue on 
the next day, and by Saturday, June 6th, a greenish tinge W 
observable, and they had attained their normal sap-green colour 
by Tuesday, June 9th. In all cases the outline of the patch 0? 
the host is more definite than in gelatine cultures. In case (2) 
a tube was infected at 11.40 A.M., Friday, June 5th, and the area 
of infection was well shown at 7.0 a.m. of the next day. By 
7.30 a.m. on Thursday, June 11th, the gelatine was liquid, and 
numerous hyphe appeared on its surface producing a “ mouldy 
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