Savory - Arachnida 1977

274 IV. DE ARACHNOLOGIA
hard. In the study of ovaries, however, these organs can be dissected
out and fixed separately. To a limited extent this is also true of silk
glands, but to little else.
The trouble caused by the hardness of the chitin has often been
avoided by using animals which have just moulted, and whose exoskeletons
are still soft; but the process of moulting is accompanied by
various internal changes, and, moreover, suitable animals are not easy
to obtain.
J\1illot ( 1926) has perfected a process by which these obstacles are
largely overcome, and his procedure is as follows.
1. Dehydrate.
2. Transfer to a mixture of ethyl ether and absolute alcohol for 12 to
24 hr, according to size.
3. To celloidine solution for 24 hr.
4. To toluene, two changes.
5. Embed in paraffin wax in the usual way.
As a fixative solution Duboscq-Brazil's or Fleming's solutions may be
used, but in general the best results are obtained by the use of the
following mixture, recommended by Petrunkevitch ( 1933) :
Alcohol, 60%
Nitric acid, sp. gr. 1·42
Eilicr
Cupric nitrate crystals
p-Nitrophenol crystals
100 cc
3 cc
Sa
2 g
5 g
Specimens may be left in this fluid as long as desired without
the tissues becoming any harder than they are in the living animal. The
fixative is washed out with three or four changes of 70% alcohol. The
best stains to use are Delafield's haematoxylin, either alone or counterstained
tetrabrom-fluoresic acid; or Mallory's triple stain.
Petrunkevitch also recommends the examination of entire specimens,
which, after fixing, have been cleared in tetrahydronaphthalene. This
makes the muscular and alimentary systems more visible. Locket and
Millidge (1951) report improved results in the examination of such
external features as epigynes if the animal is lying in phenol to which
10% of alcohol has been added.
Small arachnids like false scorpions, young spiders or young harvestmen
can be successfully cleared by soaking in warm lactic acid. They
can be mounted in Micrex or alternatively in Faure's medium, made
up thus:
32. PRACTICAL ARACHI':OLOGY
Chloral hydrate
\\"ater
Glycerin
Gum arabic (white, clear)
lOg
10 cc
2·5 cc
6g
This is made cold and is ready for use in a week.
Beech wood creosote and clO\ e oil also clear specimens and epigyncs,
while Hoyer's solution both clears and mounts pseudoscorpions, Acari
and linyphiid spiders adequately.
Lastly, Hopfmann's technique, designed in the first instance for
the examination of silk glands in spiders, may be gi\·en as follO\\·s.
1. The abdomen is fixed in Carnoy's fluid.
2. To methyl benzoate.
3. To methyl benzoate and celloidine.
4. To benzene.
5. Embed in paraffin wax.
In the study and identification of spiders the exact form of the female
epigyne and of the male palp is often of the greatest importance. The
former may be completely removed, cleaned by a moment's warming in
dilute potash and mounted. Preferable to Canada balsam is a synthetic
resin, dimethyl hydantoin formaldehyde.
The examination of the male palp is easier, though the organ itself
is often more elaborate. It may be expanded by warming in dilute
potash and either mounted or, preferably kept in a micro-vial separately
from the rest of the corpse, though in the same tube. The remO\·al of
the male organ from the abdomen of a harvestman is quite simple; it is
chitinous and tough and easily cleaned and mounted as a permanent
slide.
BEHAVIOUR
Complete knowledge of the biology of Arachnida cannot, howe\·er,
be obtained by examination of no more than their dead bodies; their
behaviour, their responses to a wide range of stimuli should also be
investigated. In this aspect of zoology the Arachnida are often found to
be excellent subjects, living with apparent contentment in captivity,
and reacting as normally to stimuli as they do in nature. Some species
are harder to keep than others, or perhaps it is more accurate to say
that the conditions necessary for their survival in cages are less easily
discovered and maintained, but this is not the general rule. Most
arachnologists have been able to observe one or more species very fully
and have described their methods. ~1illot gives very high praise to the
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