128 THE PRESERVATION OF MARINE ANIMALS
strength of 70 per cent. is to be always used for the final preserva-
tion of specimens in stoppered bottles or museum jars. When
specimens are placed first in weak alcohol, 30 per cent, is used, and
the intermediate strength to be employed is 50 per cent. Ordinary
methylated spirit is about 90 per cent. in strength, or more; that is,
it contains 10 parts of water to 90 parts of alcohol, and it must be
diluted with the proper quantity of water to obtain the other
strengths. It is sufficiently accurate to add 20 parts of water to 100
parts spirit for 70 per cent. alcohol, equal parts for 50 per cent., and
30 parts spirit to 100 parts water for 30 per cent. The most conve-
nient measure to use is cubic centimetres, the measurement being
made in tall glass jars graduated in those units.
In using corrosive sublimate and most other reagents it is
advisable to use wooden forceps and wooden rods or quills for
manipulation. The use of the fingers should be avoided as far as
possible; if they are used the hands should be well washed with
fresh water immediately afterwards. In flooding with sublimate
or acetic acid, the small vessel containing the specimen in sea
water should be placed in an empty pie dish or porcelain photo-
graphic dish, and the specimen may be washed out of the small
vessel into the larger. An enema syringe is best for large injections;
for small animals pipettes are used, made from a piece of glass tube
drawn out at one end in a gas flame, and fitted at the other into an
imperforate india-rubber teat. Finally it may be repeated that
nothing but attention and care, together with practice, can ensure
success in, preserving marine animals.
The present paper only deals with preserving specimens entire
for museum purposes. For histological microscopic investigation
and special study of organs and tissues many other methods are
in use; but, nevertheless, specimens properly preserved by the
methods mentioned above usually have their tissues in a condition
which is to some extent suitable for dissection and microscopic
study. It may be mentioned here that small portions of Hydrozoa
and Bryozoa prepared as above directed make beautiful microscopic
preparations if stained with picro-carmine and mounted in Canada
balsam in the usual way. The piece must be left in picro-carmine for
half an hour, then washed in water, transferred to successively stronger
mixtures of alcohol, and finally to absolute alcohol. After all the water
is removed by the latter, the specimen is transferred to clove oil or
turpentine, placed on a slide, a drop of Canada balsam dissolved