Molluscan Research: Techniques for collecting, handling, preparing ...

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Chemical deterioration
Byne’s ‘disease’
Micromolluscs are often fragile and prone to adverse
reaction with acids and salts. A serious destructive effect on
calcium carbonate shells is known as ‘Byne’s disease’,
named for L. St. G. Byne (1872–1947) a British amateur
shell collector who first described the phenomenon (Byne
1899a, b). Its manifestation is a white efflorescence covering
the shell, which eventually destroys the specimen
completely. Byne’s explanation that it was caused by butyric
and acetic acid was partly correct. It seems not to be caused
by shells with remaining animal tissue since the old
collections where it occurs often contain empty shells only
(pers. obs. by the authors). Tennent and Baird (1985)
identified the crystalline substance as a mixture of calcium
acetate and formiate and considered that the acetic and
formic acid originated from the oak-wood frequently used in
cabinets. The reaction can also be accelerated by low air
circulation and by high humidity, where the water molecules
act as an extractor and carrier for the acids. The necessity for
well aerated cabinets was pointed out as a precaution by
Byne (1899a, b). Some other organic substances are also
likely culprits and include cork, natural cotton, fibre-wood or
particle board, where formaldehyde-based glues are used, as
well as any surface treatment evaporating formalin as
applied for instance to some metal cabinets. All of these
substances should be avoided. A number of articles have
been written on various aspects of Byne’s disease (Kenyon
1909; Lamy 1933; Nicholls 1934; Nockert and Wadsten
1978; Padfield et al. 1982; Grosjean and Fung 1984;
Hatchfield and Carpenter 1985; Kolff 1988; Kamath et al.
1985; Davies 1987; Davies 1988; Hertz 1990; Pinto de
Oliveria and de Cassia da Silveira e Sa 1996; Stamol 1998;
Callomon 2000, 2003; de Prins 2005).
Glass ‘disease’
As in Byne’s disease, the so called ‘glass disease’
produces an efflorescence of calcium salts and, unless halted,
will lead to complete destruction of specimens in as little as
5–10 years (Fig. 5). It starts with the surface of previously
shiny specimens becoming dull, then powdery, then crystals
start forming. The shells start disintegrating and finally
crumble with only a whitish crystalline powder remaining. It
can occur in specimens that were originally perfectly dry and
repeatedly washed in fresh water and ethanol, including fatsolvents
such as perchlorethylene and carbon tetrachloride,
stored in metal cabinets in tubes with plastic closures (no
cork or cotton) and acid free archival labels. The glass
disease has hardly been mentioned in the literature (except
Kilburn 1996). Glass can release sodium hydroxide when
interacting with moisture in the air and this NaOH and any
other leaching minerals interact with the calcium carbonate
of the shell leading to the formation of sodium carbonate
powder (see Birch 2000).
Our observations indicate that the worst offenders are
high quality, high silica, heat-resistant glasses, especially cut
sections of narrow bore tubing, although the extent to which
specimen preparation and environmental parameters play a
GEIGER ET AL. (2007) MOLLUSCAN RESEARCH, VOL. 27
role in development of glass disease is an open question.
Cheap, high sodium carbonate glasses, such as disposable
culture tubes or blood test tubes are by far the better choice.
Although glass disease can be arrested in tubes containing
moisture absorbent silica gel sealed with plastic closures, by
far the simplest remedy is to avoid contact with glass by the
use of gelatine capsules if environmental conditions are
appropriate (see also above).
FIGURE 5. A. Six specimens of Skeneopsis planorbis (Fabricius,
1780) from the same lot and in the same vial from SMNH. The four
peripheral specimens are glued to paper, so the specimens were not
in direct contact with glass. The two central specimens are free,
they were in contact with the glass vial and show the white
efflorescence produced by the glass disease. Photograph AW. B.
SEM micrograph of shell affected by glass disease. Scale bar = 500
µm. Micrograph AW. C. Last surviving syntype of Anatoma
aedonia (Watson, 1886) (BMNH 1887.2.9.398); the remainder had
crumbled to dust. Uncoated specimen in variable pressure SEM.
Scale bar = 1 mm. Micrograph DLG. D. Detail of efflorescence
from specimen shown in B. Scale bar = 30 µm. Images AW.
Preparation of micromollusc shells for SEM
Cleaning
Whenever possible, select the cleanest shells available
for SEM. Delicate specimens can be cleaned with a fine-