THE ESSEX FIELD CLUB.
33
Smith made some general observations on the necessity for light experienced
by lichens, such need rising with the lowering of the temperature, and
being greatest on the tundras of the far North. Lichens which grew on
open moors, or on roofs or exposed rock-faces, experienced more direct
exposure to strong sunlight than those which grew on tree-trunks, and such
exposure affected their colour when very great, hence the dark brown
tints, sometimes almost black, of alpine rock-forms. Such a lichen
as Physcia parietina owed its orange hue to the presence of an acid, which
protected the thallus from the too ardent action of light, and the colour
changed according to the light-intensity to which the individual specimen
happened to be subjected.
Mr. Percy Thompson referred to the remarks he had made on the
occasion of the last visit of the Club to Theydon Bois in December 1914
(see ante, p. 27), with regard to the successive colonisation of a burnt patch
of forest ground, first by the moss Funaria hygrometrica, and next by a
lichen, Peltigera spuria, which last had in its turn given way to the invasion
of the ordinary heath-flora of the district. He added that the party had
that day paid another visit to the burnt patch of heathland, and had dis-
covered only a few sickly specimens of the lichen remaining, almost over-
grown by grasses and other heath plants, and attacked also by a parasitic
fungus Illosporium carneum, which appears as small pink eruptions upon
the surface of the lichen-thallus. Mr. Thompson said it was clear that
the appearance of the fungus was the last stage in the history of the
Peltigera, so far as that particular patch of ground was concerned.
Mr. E. M. Holmes having left early on account of distance from home,
Mr. Sherrin reported the finding of the moss, Catharinea undulata, var,
minor, that day as noteworthy, as it appeared to be its first record from
Epping Forest. He thought that no uncommon Hepatic had been met
with during the day, but several forms had been seen in fruit.
Mr. Ross said he had noted 14 or 15 Hepatics during the day's ramble.
Mr. Nicholson exhibited specimens of flowers of the Common Gorse
(Ulex europaeus) found during the day at Theydon Bois, which showed the
small reflexed lobes to the vexillum to which the club's attention had
already been drawn by Mr. W. Howard at a recent meeting. Some of the
flowers exhibited this peculiarity on one side only of the standard, others
on both sides; and the lobe is observable even in the unopened bud, A
discussion ensued on the exhibit and the suggestion was hazarded that
the reflexed margin might possibly serve a useful purpose in connection
with the visits of bees, and Mr. Nicholson was asked to keep observation
on the flowers during the coming summer.
At 7 o'clock the little company broke up, and wended its way through
the murk to Theydon Bois station, homeward bound.
[The Editor is indebted to Mr. Percy Thompson's kindness for the
above report.]
ANNUAL MEETING AND 447th ORDINARY MEETING.
Saturday, 27TH March 1915.
These meetings took place as usual in the Municipal Technical Institute,
Stratford.
The President, Mr. S. Hazzledine Warrem, F.G.S., took the chair
C