Glass capsules (Fig. 8) are made in different sizes, ranging from 1½
in. to 3 in. in diameter, with a height of 1 in. or 2 in. The largest
size, 3 in. by 2 in., costs 5_d._, and a glass circle to cover it,
1_d._ These capsules will be found useful for small aquaria, and
for isolating aquatic larvae in order to keep them under observation
during their change to perfect insects. It was in a capsule of this
kind that some of my Ptychoptera larvae (p. 184) were kept, and changed
into the pupal condition.
The glass block, with cover (Fig. 9), is convenient for a number of
purposes. In it small creatures may be examined in air or in water, and
it makes an exceedingly convenient little dissecting dish for use with
the mounted hand magnifier (Fig. 1), or with Leitz’s stand (Fig. 3), or
the home-made stand (Fig. 6). The glass box, with cover (Fig. 10), is
extremely good for keeping small creatures under observation.
[Illustration: FIG. 9.--Glass Block, with cover.]
[Illustration: FIG. 10.--Glass Box, with cover.]
Excavated glass slips, 3 in. by 1 in., may be bought from any optician.
They serve for the examination of objects in water, and also for
dissection. The best I have been able to get have been supplied by Mr.
J. Hornell, of the Biological Laboratory, Jersey, and they are very
cheap.
We shall need some forceps to pick up specimens from the vessels
in which they are kept, and the same little instruments will be
found convenient in collecting. Both forms have advantages of their
own; if we are limited to one pair, they should be curved, and of
brass. Forceps with ivory tips are very useful for handling aquatic
vegetation. These articles are not usually sold by opticians, but
are kept by the tradesmen in Clerkenwell who sell jewellers’ and
watchmakers’ tools, and cost from 1_s._ to 1_s._ 6_d._ a
pair.
[Illustration: FIG. 11.--Forceps.]
Dipping-tubes are used to take up small aquatic animals from the
vessels in which they are kept. Very little practice will render the
use of this instrument easy. The tube is held firmly between the thumb
and the third and fourth fingers of either hand, while the index finger
is pressed firmly on the top. Most people naturally prefer the right
hand, but it is well to accustom oneself to use the right or left
indifferently. The open end is then put into the water, just over the
object to be secured, and the index finger lifted. The rush of water
into the tube will carry the object into it, and if the finger be again
applied to the top, the pressure of the atmosphere will prevent the
water from escaping when the tube is lifted out[5].
Small brushes are useful for taking up specimens from the water or from
pickle; common ones will do very well for large objects, but for small
objects and parts it is advisable to have one or two sable brushes, as
these form a better point.
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