46
THE ESSEX FIELD CLUB.
Epping Forest. Almost immediately after the stumps were cut the slimy layers
of this curious organism had spread with rapidity over the sap-bathed surface.
The fungus consisted of masses of naked protoplasm, having considerable powers
of movement, like the Amoeba, although botanists now consider the Myxomycetes
to be fungal, and not animal, in their nature.
Mr. H. C. Snell exhibited several specimens of the somewhat rare subter-
ranean slug, Testacella scutulum, which he had found during this season's spring-
digging in his garden at Buckhurst Hill. The creature is very interesting in its
habits, being carnivorous, and feeding upon earth-worms, which it hunts under-
ground. Mr. Cole remarked that Mr. Crouch had found the slug at Wanstead,
and he himself had taken it somewhat abundantly in an old garden at Stoke
Newington, many years ago.
Mr. Oldham exhibited species of Noctuae captured in Epping Forest during
the last autumn, and Mr. Wire explained an admirable system he had devised for
mounting, indexing, and grouping in volumes, newspaper cuttings, leaflets, and
small pamphlets.
Prof. Meldola said that Col. Swinhoe, M.A., F.L.S., of Oxford, had intended
to give them a lecture on "Protection in Nature"; but most unfortunately,
owing to sudden illness, he was unable to leave home. In the kindest manner,
their member, Mr. E. B. Poulton, M.A., F.R.S., had come to their rescue,
travelling specially from Oxford that afternoon to deliver a lecture on very
similar lines to those which had been proposed by Col. Swinhoe.
Mr. Poulton then delivered a most interesting address, which was illustrated
by a large number of coloured pictures from original drawings (shown by the
oxy-hydrogen lantern) of various animals considered from the point of view of
their powers of concealment or other modes of protection from their enemies.
Mr. Poulton clearly showed that not only have animals the power of concealment
when the conditions of environment are constant, as when they resembled sand,
rocks, bark of trees, etc., but that many animals, particularly insects, had the
power of adaptation to varying surroundings. The colour of oceanic animals
frequently assimilated in a truly wonderful way to the tint of the sea or the
prevailing colour of the seaweeds, etc. Land animals often resembled the sand,
rocks, or twigs of trees, or dead leaves, etc., upon which they rested. The
lecturer explained a series of examples drawn from a wide range of animal life,
showing the modes of concealment acquired by fish, crustacea, spiders, insects,
etc.. The most interesting part of the address was that in which Mr. Poulton
detailed the results of his own researches upon the varying colour relations of
caterpillars and chrysalids with their surroundings. Perhaps the most remark-
able example was the caterpillar of our common "Peppered moth" (Amphydasis
betularia), which varied in a most startling way in accordance with the prevailing
tint of the twigs or leaves upon which it happened to rest. By a series of skil-
fully conducted experiments, Mr. Poulton had proved that it was possible to
obtain from the same batch of eggs of the moth, caterpillars differing most
widely in colour, simply by varying the tints of the surrounding objects.
Cocoons and chrysalids of moths and butterflies were shown to vary in a similar
manner. The lecturer showed that the variation was not the effect of food, as had
been formerly supposed, but that it was the result of the action of light upon the
superficial tissues of the caterpillars, whereby they were rendered opaque or
transparent, so concealing or revealing the colours of the deeper situated tissues
in the bodies of the animals. Mr. Poulton concluded by exhibiting the coloured