National Geographic Bresser 40X-640X Mode D'emploi page 14

glass container in a bright location, but don't put it in direct sunlight. Since you have a hatchery, you cal also add
the salt solution along with a few eggs to each of the four compartments of the tank. The temperature should
be around 25º. At this temperature, the shrimps will hatch in about 2-3 days. If the water in the glass evaporates,
add some water from the second container.
The Brine Shrimp under the Microscope
The animal that hatches from the egg is known by the name "nauplius larva." With the help of a pipette,
you can place a few of these larvae on a glass slide and observe them. The larvae will move around in the
salt water by using their hair-like appendages. Take a few larvae from the container each day and observe
them under the microscope. In case you've hatched the larvae in a hatchery, simply take off the cover of
the tank and place the tank on the stage. Depending on the room temperature, the larvae will be mature in
6-10 weeks. Soon, you will have had raised a whole generation of brine shrimp, which will constantly grow
in numbers.
Feeding your Brine Shrimp
In order to keep the brine shrimp alive, they must be fed from time to time, of course. This must be done
carefully, since overfeeding can make the water become foul and poison our shrimp population. The feed-
ing is done with dry yeast in powdered form. A little bit of this yeast every second day is enough. If the water
in the compartments of the hatchery or your container turns dark, that is a sign that it is gone bad. Take the
shrimp out of the water right away and place them in a fresh salt solution.
Warning!
The shrimp eggs and the shrimp are not meant to be eaten!
7.2. Textile fibres
Objects and accessories:
1. Threads of different textiles: Cotton, linen, wool, silk, Celanese, nylon and any others you can find.
2. Two needles:
Put each thread on a glass slide and fray each with the help of the two needles. Put a drop of water over
each thread with the pipette and cover each with a cover glass. Adjust the microscope to a low magnifica-
tion. Cotton fibres are of plant origin and look, under the microscope, like a flat, twisted band. The fibres are
thicker and rounder at the edges than in the centre. Cotton fibres consist primarily of long, collapsed tubes.
Linen fibres are also of plant origin; they are round and run in straight lines. The fibres shine like silk and
exhibit numerous swellings along the shaft of the fibre. Silk is of animal origin and consists of solid fibres
of smaller diameter than the hollow vegetable fibres. Each silk fibre is smooth and even and has the appear-
ance of a small glass rod. Wool fibres are also of animal origin; the surface consists of overlapping scales,
which appear broken and wavy. If possible, compare wool fibres from different weaving mills, and note the
differences in the appearance of the fibres. Experts can determine the country of origin of wool based on
its appearance under a microscope. Celanese is artificially manufactured by a long chemical process. All
Celanese fibres show hard, dark lines on a smooth, shining surface. The fibres crinkle in the same way after
drying. Observe the similarities and differences between the different fibres.
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