258 MR. W. H. BURRELIi ON THE ;ECID1UM ELATINUM IN NORFOLK. 
that infection takes place in twigs which have just escaped from 
the bud. Hartig suggests that the germ tube gains an entrance 
through wounds in the cortex. If a bud capable of development 
exists near the point of entrance, the mycelium keeps pace with 
its growth, modifying its structure as previously described, and 
causing a Witches broom ; if no bud be present a canker is formed, 
but in either case the effect is limited, the tissues on either side of 
the gall remaining normal. 
The leaves produced on the affected twigs are pale yellowish 
green, from the almost entire absence of chlorophyll. On the upper 
surface spermogonia appear about May ; a month or two later 
aecidia are formed on the under surface, and the leaves commence 
to fall in August when the aecidiospores have dispersed. The 
internal structure of the leaves undergoes proportionate changes. 
As it was not till December that I had any clue to the nature of 
the growth, I have only had an opportunity of examining the few 
leaves, which probably, from their late development, escaped the 
more vigorous attacks of the fungus and retained their position till 
mid-winter. These show a very feeble development of the two 
central vascular bundles ; the resin ducts and palisade-parenchyma 
of the upper surface are suppressed, and an orange-coloured stain 
which occurs here and there shows through the lower epidermis as 
a double row of rust spots. I have not been able to detect in 
these leaves any clearly defined basidia, spores, or pseudoperidial 
cells. 
There are an appreciable number of diseased trees in the neigh- 
bourhood of Sheringham. On Mr. Upcher’s estate there are some 
half-dozen brooms. Westward, on the Weybourne Hall estate, there 
are very few Silver Firs, and these appear to be clean. Eastward, 
the search was more productive ; single brooms here and there led 
to a patch of woodland on the adjoining estates of Mr. Cremer and 
Sir Samuel Hoare, where there are at least fifty trees affected, and 
from there I have traced isolated cases through Beeston 'Regis to 
Aylmerton. An afternoon at Hempstead, near Holt, gave no definite 
results. One tree had a suspicious looking growth which was too 
high up to examine closely, and two or three other trees had cankers 
and dead brooms, but in the absence of well-marked characters 
I hesitate to refer them to sEcidium elatinum. 
