OF EPPING FOREST.
285
Another method of exhibition, which has been made
use of at the British Museum, is the preparation of coloured
wax models of the galls and of the plants upon which
they grow. As regards oak galls, such as Trigonaspis cr ustalis,
both generations are shown in the same case, Trigonaspis remum
appearing on the leaves and T. crustalis from the adventitious
buds on the trunk. There is often a tendency to depict "good
specimens" by exaggerating the size and number of the galls,
and this should be guarded against as giving a wrong impression
to anyone who is just starting to collect, who is not always quite
certain what to look for. [I have found that a solution of
formalin (about 5 per cent. of the 40 per cent. commercial
formalin) preserves the form of most galls, but any colour
dependent upon chlorophyll or its derivatives disappears in the
course of time. We are now trying in the museum a method of
bleaching with sodium hypochlorite, which discharges all colour
and produces a semi-transparency, displaying form and structure
excellently well, the specimens being "put up" in go per cent-
alcohol. Of course, as Mr. Lewis says, such preparations should
be placed alongside drawings giving the natural colours of the
galls.—W. Cole.]
Classification.
Since the discovery by Dr. Adler of the alternating agami
and sexal generations among the oak gall-makers, the nomencla-
ture has undergone, a change. The method adopted by Mr.
Cameron is the truly scientific one, but these alternating genera-
tions present such variations that the generic names used by Dr.
Adler,5 which serve to differentiate more clearly between the
agamic and sexual forms, are still adhered to in many cases. I
have, therefore, inserted a list showing the differences between
the nomenclature of these two authors.
In the case of the three forms, Andricus fecundatrix, Andricus
malpighii and Dryophania divisa, I have found galls of the agamic
generation only, and have been unable to find specimens of the
corresponding sexual generations, Andricus pilosus, A. nudus and
Dryophania verucosus respectively, so that in this list these latter
have been printed in italics. I have inserted them partly because
in giving an account of the generation cycle they must necessarily
5 Alternating Generations. A Biological Study of the Oak Galls and Gall Flics. By
Hermann Adler, M.D., Schleswig, Translated and Edited by Charles R. Straton. F.R.G.S.,
F.E.S. Oxford 1894.